Supplemental Prospectus (Form 424B5)

Filed Pursuant to Rule 424(b)(5)
Registration Statement No. 333-291294

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is comprised of two parts. The first is this prospectus supplement, which describes the specific terms of this offering. The second part, the accompanying prospectus, gives more general information, some of which may not apply to this offering. This prospectus supplement also adds to, updates and changes information contained in the accompanying prospectus. If the information set forth in this prospectus supplement differs in any way from the information in the accompanying prospectus, you should rely on the information in this prospectus supplement. If the information set forth in this prospectus supplement conflicts with any statement in a document we have incorporated by reference, then you should consider only the statement in the more recent document.

The accompanying prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the "SEC") using a shelf registration statement. Under the shelf registration process, from time to time, we may offer and sell debt securities, including the subordinated debt securities offered hereby, preferred shares, depositary shares, common stock, warrants, rights, purchase contracts or units, or any combination thereof, in one or more offerings.

It is important that you read and consider all of the information contained in this prospectus supplement, the accompanying prospectus and any free writing prospectus filed by us with the SEC related to this offering in making your investment decision. You should also read and consider the information in the documents to which we have referred you in "Incorporation of Certain Documents by Reference" on page S-iii of this prospectus supplement and "Where You Can Find More Information" on page 4 of the accompanying prospectus.

We have not, and the underwriters have not, authorized any other person to provide you with any information other than the information contained in this prospectus supplement, the accompanying prospectus, any free writing prospectus we may authorize to be delivered to you and the documents incorporated by reference herein and therein. Neither we nor the underwriters take responsibility for, or provide any assurance as to the reliability of, any different or additional information. This prospectus supplement, the accompanying prospectus and any free writing prospectus do not constitute, and may not be used in connection with, an offer or solicitation by anyone in any jurisdiction in which such offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to any person to whom it is unlawful to make such offer or solicitation. The information contained in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference herein or therein or any free writing prospectus prepared by us is only accurate as of the date of the document containing such information, regardless of the time of delivery of this prospectus supplement and any sale of the subordinated notes. Our business, financial condition, results of operations and prospects may have changed since that date.

The information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus is not investment, legal or tax advice. You should consult your own legal counsel, accountants and other advisers for legal, tax, business, financial and related advice before investing in the subordinated notes.

The distribution of this prospectus supplement, the accompanying prospectus and any free writing prospectus and the offering of the subordinated notes in certain jurisdictions may be restricted by law. Persons into whose possession this prospectus supplement, the accompanying prospectus and any free writing prospectus come should inform themselves about and observe any such restrictions.

In this prospectus supplement, references to "First Financial," the "Company," "we," "our" and "us" and similar terms mean First Financial Bancorp. and its subsidiaries, unless the context otherwise requires.

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EXTENDED SETTLEMENT

We expect that delivery of the subordinated notes will be made against payment therefor on or about    , 2025, which will be the    business day following the date of pricing of the subordinated notes, or "T+ ." Under Rule 15c6-1 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), trades in the secondary market generally are required to settle in one business day, unless the parties to any such trade expressly agree otherwise. Accordingly, purchasers who wish to trade the subordinated notes prior to the business day before delivery of the subordinated notes will be required, by virtue of the fact that the subordinated notes initially settle in T+ , to specify an alternate settlement arrangement at the time of any such trade to prevent a failed settlement. Purchasers of the subordinated notes who wish to trade the subordinated notes prior to their date of delivery hereunder should consult their advisors.

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public on the SEC's website at www.sec.gov and on the investor relations page of our website at www.bankatfirst.com. Except for those SEC filings incorporated by reference in this prospectus supplement, the contents of our website are not part of this prospectus, and the reference to our website does not constitute incorporation by reference in this prospectus of the information contained at that website.

In this prospectus supplement and the accompanying prospectus, as permitted by law, we "incorporate by reference" information from other documents that we file with the SEC. This means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be a part of this prospectus supplement and the accompanying prospectus and should be read with the same care. When we update the information contained in documents that have been incorporated by reference by making future filings with the SEC, the information incorporated by reference in this prospectus supplement and the accompanying prospectus is considered to be automatically updated and superseded. In other words, in case of a conflict or inconsistency between information contained in this prospectus supplement and the accompanying prospectus and information incorporated by reference into this prospectus, you should rely on the information contained in the document that was filed later.

We incorporate by reference the following documents listed below:

In addition, all reports and other documents we subsequently file pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act on or after the date of this prospectus supplement and the accompanying prospectus until we complete the offering of the subordinated notes offered by this prospectus supplement (other than any information furnished pursuant to Item 2.02 or Item 7.01 of any Current Report on Form 8-K, unless we specifically state in such Current Report that such information is to be considered "filed" under the Exchange Act or we incorporate it by reference into a filing under the Securities Act of 1933, as amended (the "Securities

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Act"), or the Exchange Act) will be deemed to be incorporated by reference in this prospectus supplement and the accompanying prospectus and to be part of this prospectus supplement and the accompanying prospectus from the date of the filing of such reports and documents.

Any statement contained in this prospectus supplement, the accompanying prospectus or in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this prospectus supplement and the accompanying prospectus to the extent that a statement contained in any subsequently filed document which is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement and the accompanying prospectus.

We will provide to each person to whom a prospectus supplement is delivered, a copy of any or all of the information that has been incorporated by reference in the prospectus supplement but not delivered with the prospectus. You may request a copy of these filings, other than an exhibit to a filing unless that exhibit is specifically incorporated by reference into that filing, at no cost, by writing to or telephoning us at the following address:

First Financial Bancorp.

255 East Fifth Street

Suite 700

Cincinnati, Ohio 45202

Attention: Investor Relations

(877) 322-9530

In addition, these filings are available on our website at www.bankatfirst.com. Please note that this website address is for textual reference only and the information on our website is not a part of, and is not incorporated into, this prospectus or any applicable prospectus supplement.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING INFORMATION

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein may contain forward-looking statements within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. In addition, we may make forward-looking statements orally or in writing to investors, analysts, members of the media, or others. Forward-looking statements reflect our current expectations, estimates or projections concerning future results or events. In some cases, you can identify these statements by forward-looking words such as "may," "might," "will," "should," "expects," "intends," "plans," "anticipates," "believes," "estimates," "predicts," "potential" or "continue," the negative of these terms and other comparable terminology. These forward-looking statements, which are subject to risks, uncertainties and assumptions (some of which are beyond our control and ability to predict), may include projections of our future financial performance, future expenses, anticipated growth strategies, descriptions of new business initiatives and anticipated trends in our business or financial results. These statements are not guarantees of future performance and are only predictions based on our current expectations and projections about future events. Undue reliance should not be placed on forward-looking statements. Among the important factors that could cause the Company's actual financial condition and results of operations, level of activity, performance or achievements to differ materially from those indicated by such forward-looking statements are the factors disclosed under "Risk Factors" in Item 1A of our most recent Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on February 20, 2025, as such factors may be updated from time to time in our periodic filings with the SEC, as well as the other information contained or incorporated by reference in this prospectus supplement or the accompanying prospectus. Forward-looking statements speak only as of the date on which such statements are made. Except as required by law, we undertake no obligation to update any forward-looking statement to reflect events or circumstances after the date on which such statement is made, or to reflect the occurrence of unanticipated events.

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While no list of assumptions, risks, or uncertainties could be complete, some of the factors that may cause actual results or other future events or circumstances to differ from those in forward-looking statements include:

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RISK FACTORS

An investment in the subordinated notes involves certain risks. You should carefully consider the risk factors and other information included or incorporated by reference in this prospectus supplement and the accompanying prospectus before making an investment decision. In particular, you should carefully consider, among other things, the matters discussed below and under "Risk Factors" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024. Our business, financial condition and results of operations could be materially adversely affected by any of these risks. The price of the subordinated notes could decline due to any of these risks, and you may lose all or part of your investment. This prospectus supplement and the accompanying prospectus also contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks faced by us described below and elsewhere in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein. The prospectus supplement is qualified in its entirety by those risk factors.

Risk Factors Related to the Subordinated Notes

You should not rely on indicative or historical data concerning SOFR.

The interest rate during the floating rate period will be determined using Three-Month Term SOFR (unless a Benchmark Transition Event and its related Benchmark Replacement Date occur with respect to Three-Month Term SOFR, in which case the rate of interest will be based on the next-available Benchmark Replacement). In the following discussion of the Secured Overnight Financing Rate ("SOFR"), when we refer to SOFR-linked subordinated notes, we mean the subordinated notes at any time when the interest rate on the subordinated notes is or will be determined based on SOFR, including Three-Month Term SOFR.

SOFR is published by the Federal Reserve Bank of New York ("FRBNY") and is intended to be a broad measure of the cost of borrowing cash overnight collateralized by U.S. Treasury securities. FRBNY reports that SOFR includes all trades in the Broad General Collateral Rate, plus bilateral U.S. Treasury repurchase agreement ("repo") transactions cleared through the delivery-versus-payment service offered by the Fixed Income Clearing Corporation (the "FICC"), a subsidiary of The Depository Trust & Clearing Corporation ("DTCC"). SOFR is filtered by FRBNY to remove a portion of the foregoing transactions considered to be "specials." According to FRBNY, "specials" are repos for specific-issue collateral which take place at cash-lending rates below those for general collateral repos because cash providers are willing to accept a lesser return on their cash in order to obtain a particular security.

FRBNY reports that SOFR is calculated as a volume-weighted median of transaction-level tri-party repo data collected from The Bank of New York Mellon, which currently acts as the clearing bank for the tri-party repo market, as well as general collateral finance repo transaction data and data on bilateral U.S. Treasury repo transactions cleared through the FICC's delivery-versus-payment service.

FRBNY states that it obtains information from DTCC Solutions LLC, an affiliate of DTCC. FRBNY currently publishes SOFR daily on its website. FRBNY states on its publication page for SOFR that use of SOFR is subject to important disclaimers, limitations and indemnification obligations, including that FRBNY may alter the methods of calculation, publication schedule, rate revision practices or availability of SOFR at any time without notice.

On July 29, 2021, the Alternative Reference Rates Committee (the "ARRC") convened by the Federal Reserve and FRBNY formally recommended the use of the CME Group's computation of forward-looking SOFR

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term rates, which are calculated by the CME Group based on SOFR futures. It is currently anticipated that Three-Month Term SOFR, for purposes of the subordinated notes, will be based on the CME Group's forward-looking SOFR term rates with a tenor of three months. FRBNY started publishing SOFR in April 2018. FRBNY has also started publishing historical indicative SOFRs dating back to 2014, although such historical indicative data inherently involves assumptions, estimates and approximations. You should not rely on such historical indicative data or on any historical changes or trends in SOFR as an indicator of the future performance of SOFR.

The amount of interest payable on the subordinated notes will vary on and after    , 2030.

As the interest rate of the subordinated notes will be calculated based on SOFR from    , 2030 to, but excluding, the maturity date or earlier redemption date and SOFR is a floating rate, the interest rate on the subordinated notes will vary on and after    , 2030. During this period, the subordinated notes will bear a floating interest rate set each quarterly interest period at a per annum rate equal to the Benchmark rate (which is expected to be Three-Month Term SOFR) plus a spread of      basis points; provided, that in the event the Benchmark rate is less than zero, then the Benchmark rate shall be deemed to be zero. The per annum interest rate that is determined on the relevant determination date will apply to the entire quarterly interest period following such determination date even if the Benchmark rate increases during that period.

Floating rate notes bear additional significant risks not associated with fixed rate debt securities. These risks include fluctuation of the interest rates and the possibility that you will receive an amount of interest that is lower than expected. We have no control over a number of matters, including economic, financial, and political events, that are important in determining the existence, magnitude, and longevity of market volatility and other risks and their impact on the value of, or payments made on, the floating rate subordinated notes.

SOFR may be more volatile than other benchmark or market rates.

Since the initial publication of SOFR, daily changes in the rate have, on occasion, been more volatile than daily changes in comparable benchmark or market rates, and SOFR over time may bear little or no relation to the historical actual or historical indicative data. In addition, the return on and value of the SOFR-linked subordinated notes may fluctuate more than floating rate securities that are linked to other rates.

Changes in SOFR could adversely affect the amount of interest that accrues on the SOFR-linked subordinated notes and the trading prices for the SOFR-linked subordinated notes.

Because SOFR is published by FRBNY based on data received from other sources, we have no control over its determination, calculation or publication. There can be no assurance that SOFR will not be discontinued or fundamentally altered in a manner that is materially adverse to the interests of investors in the SOFR-linked subordinated notes. If the manner in which SOFR is calculated is changed, that change may result in a reduction in the amount of interest that accrues on the SOFR-linked subordinated notes, which may adversely affect the trading prices of the SOFR-linked subordinated notes. In addition, the interest rate on the SOFR-linked subordinated notes for any day will not be adjusted for any modification or amendment to SOFR for that day that FRBNY may publish if the interest rate for that day has already been determined prior to such publication. Further, if the Benchmark rate on the SOFR-linked subordinated notes during the floating rate period for any interest period declines to zero or becomes negative, interest will only accrue on the SOFR-linked subordinated notes at a rate equal to the spread of     % per annum with respect to that interest period. There is no assurance that changes in SOFR could not have a material adverse effect on the yield on, value of and market for the SOFR-linked subordinated notes.

Any failure of SOFR to maintain market acceptance could adversely affect the subordinated notes.

SOFR was developed for use in certain U.S. dollar derivatives and other financial contracts as an alternative to the London Interbank Offered Rate, or LIBOR, in part because it is considered a representation of general

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funding conditions in the overnight U.S. Treasury repurchase agreement market. However, as a rate based on transactions secured by U.S. Treasury securities, SOFR does not measure bank-specific credit risk and, as a result, is less likely to correlate with the unsecured short-term funding costs of banks. This may mean that market participants would not consider SOFR a suitable replacement or successor for all of the purposes for which LIBOR historically has been used (including, without limitation, as a representation of the unsecured short-term funding costs of banks), which may, in turn, lessen market acceptance of SOFR. Any failure of SOFR to maintain wide market acceptance could adversely affect the return on and value of the subordinated notes and the price at which investors can sell the subordinated notes in the secondary market.

Any market for the SOFR-linked subordinated notes may be illiquid or unpredictable.

Since SOFR is a relatively new market index, SOFR-linked debt securities likely will have no established trading market when issued, and an established trading market for the SOFR-linked subordinated notes may never develop or may not be very liquid. Market terms for securities that are linked to SOFR, such as the spread over the base rate reflected in the interest rate provisions, may evolve over time, and as a result, trading prices of the SOFR-linked subordinated notes may be lower than those of later-issued securities that are linked to SOFR. Similarly, if SOFR does not prove to be widely used in securities that are similar or comparable to the SOFR-linked subordinated notes, the trading price of the SOFR-linked subordinated notes may be lower than those of securities that are linked to rates that are more widely used. You may not be able to sell the SOFR-linked subordinated notes at all or may not be able to sell the SOFR-linked subordinated notes at prices that will provide you with a yield comparable to similar investments that have a developed secondary market, and may consequently suffer from increased pricing volatility and market risk. The manner of adoption or application of reference rates based on SOFR in the bond and equity markets may differ materially compared with the application and adoption of SOFR in other markets, such as the derivatives and loan markets. You should carefully consider how any potential inconsistencies between the adoption of reference rates based on SOFR across these markets may impact any hedging or other financial arrangements which you may put in place in connection with any acquisition, holding or disposal of the SOFR-linked subordinated notes.

Any Benchmark Replacement may not be the economic equivalent of Three-Month Term SOFR.

Under the benchmark transition provisions of the subordinated notes, if the calculation agent determines that a Benchmark Transition Event and its related Benchmark Replacement Date have occurred with respect to Three-Month Term SOFR, then the interest rate on the subordinated notes during the floating rate period will be determined using the next-available Benchmark Replacement (which may include a related Benchmark Replacement Adjustment). However, the Benchmark Replacement may not be the economic equivalent of Three-Month Term SOFR. For example, Compounded SOFR, the first available Benchmark Replacement, is the compounded average of the daily Secured Overnight Financing Rates calculated in arrears, while Three-Month Term SOFR is intended to be a forward-looking rate with a tenor of three months. In addition, very limited market precedent exists for securities that use Compounded SOFR as the rate basis, and the method for calculating Compounded SOFR in those precedents varies. Further, the ISDA Fallback Rate, which is another Benchmark Replacement, has not yet been established and may change over time.

The implementation of Benchmark Replacement Conforming Changes could adversely affect the amount of interest that accrues on the subordinated notes and the trading prices for the subordinated notes.

Under the benchmark transition provisions of the subordinated notes, if a particular Benchmark Replacement or Benchmark Replacement Adjustment cannot be determined, then the next-available Benchmark Replacement or Benchmark Replacement Adjustment will apply. These replacement rates and adjustments may be selected or formulated by (i) the Federal Reserve and/or the FRBNY, or a committee officially endorsed or convened by the Federal Reserve and/or the FRBNY or any successor thereto (the "Relevant Governmental Body") (such as the ARRC), (ii) International Swaps and Derivatives Association, Inc., or any successor thereto

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("ISDA") or (iii) in certain circumstances, the calculation agent. In addition, the benchmark transition provisions expressly authorize the calculation agent to make certain changes, which are defined in the terms of the subordinated notes as "Benchmark Replacement Conforming Changes," with respect to, among other things, the determination of interest periods, and the timing and frequency of determining rates and making payments of interest. The application of a Benchmark Replacement and Benchmark Replacement Adjustment, and any implementation of Benchmark Replacement Conforming Changes, could result in adverse consequences to the amount of interest that accrues on the subordinated notes during the floating rate period, which could adversely affect the return on, value of and market for the subordinated notes. Further, there is no assurance that the characteristics of any Benchmark Replacement will be similar to the then-current Benchmark that it is replacing, or that any Benchmark Replacement will produce the economic equivalent of the then-current Benchmark that it is replacing.

A change in the Benchmark may be treated as a significant modification of the subordinated notes for tax purposes, which could result in taxable gain or loss to holders.

If a term of the subordinated notes, such as the interest rate, is altered and the degree to which the subordinated notes are altered is economically significant, the subordinated notes will be treated as exchanged for the modified notes for federal tax purposes. A deemed exchange of the subordinated notes could result in gain or loss to the holders. Thus, if the Benchmark is replaced with a rate other than the Three-Month Term SOFR, such replacement could adversely affect the holders of the subordinated notes.

Because the subordinated notes may be redeemed at our option under certain circumstances prior to their maturity, you may be subject to reinvestment risk.

Subject to the prior approval of the Federal Reserve, to the extent that such approval is then required, we may redeem the subordinated notes at our option (i) in whole or in part beginning with the interest payment date of     , 2030, and on any interest payment date thereafter. In addition, at any time at which any subordinated notes remain outstanding, subject to the prior approval of the Federal Reserve, to the extent that such approval is then required, we may redeem the subordinated notes in whole but not in part upon the occurrence of (i) a "Tier 2 Capital Event," (ii) a "Tax Event" or (iii) if we are required to register as an investment company pursuant to the 1940 Act. In the event that we redeem the subordinated notes, holders of the subordinated notes will receive only the principal amount of the subordinated notes plus any accrued and unpaid interest to, but excluding, such earlier redemption date. If any redemption occurs, holders of the subordinated notes will not have the opportunity to continue to accrue and be paid interest to the stated maturity date. Any such redemption may have the effect of reducing the income or return that you may receive on an investment in the subordinated notes by reducing the term of the investment. If this occurs, you may not be able to reinvest the proceeds at an interest rate comparable to the rate paid on the subordinated notes. See "Description of Subordinated Notes-Redemption."

If we are in default on our obligations to pay our Senior Indebtedness, we will not be able to make payments on the subordinated notes.

Our obligations under the subordinated notes will be unsecured and will rank junior to the following, unless, by their terms, the obligation ranks equal with, or junior to, the subordinated notes:

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If we default on payments under any of these obligations that are senior to the subordinated notes, or if any of these senior obligations are accelerated or any judicial proceeding with respect to a default is pending, we will not be able to make payments on the subordinated notes, unless we cure the default. Additionally, the subordinated notes will rank pari passu with our outstanding 5.25% subordinated notes due 2030. If we liquidate, go bankrupt or dissolve, we would be able to pay under the subordinated notes only after we have paid in full all of our liabilities that are senior to the subordinated notes. As of September 30, 2025, we had $27.8 million of Senior Indebtedness outstanding on a consolidated basis. The Subordinated Indenture (as defined below) does not limit the amount of Senior Indebtedness that we may incur. For more information on the subordination of payments under the subordinated notes, see "Description of Subordinated Notes-Subordination."

The subordinated notes are structurally subordinated to all indebtedness of our subsidiaries and creditors of our subsidiaries will have priority as to our subsidiaries' assets.

The subordinated notes are not obligations of, or guaranteed by, any of our subsidiaries or any third party. As a result, our right and the rights of our creditors, including holders of the subordinated notes, to participate in any distribution of assets of any of our subsidiaries upon its liquidation, reorganization or otherwise would be subject to the prior claims of creditors of that subsidiary. In the event of any such distribution of assets of our bank subsidiary, First Financial Bank, the claims of depositors and other general or subordinated creditors of First Financial Bank would be entitled to priority over the claims of ours or holders of the subordinated notes. Accordingly, the subordinated notes are structurally subordinated to all of the existing and future liabilities and obligations of our subsidiaries. Claims on First Financial Bank by creditors other than us include those by holders of our long-term debt and there are substantial obligations with respect to deposit liabilities and federal funds purchased, other short-term borrowings and various other financial obligations. As of September 30, 2025, we had $27.8 million of Senior Indebtedness outstanding on a consolidated basis, and First Financial Bank had $14.4 billion of deposits, $550.0 million of FHLB advances, and $45.2 million of other short term borrowings to which the subordinated notes will be structurally subordinated.

We are a holding company, and banking laws and regulations could limit our access to funds from First Financial Bank with the result that we may not have access to sufficient cash to make payments on the subordinated notes.

As a holding company, our principal source of funds to service our debt, including the subordinated notes, is dividends from our subsidiaries. For the year ended December 31, 2024, our interest expense on our debt obligations was $18.4 million (holding company only).

Federal and state banking regulations limit dividends from First Financial Bank to us. Generally, banks are prohibited from paying dividends when doing so would cause them to fall below regulatory minimum capital levels. Additionally, limits exist on banks paying dividends in excess of net income for specified periods. The

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total amount available for payment of dividends by First Financial Bank was approximately $230.5 million at September 30, 2025, based on First Financial Bank maintaining enough capital to be considered well capitalized and other regulatory restrictions on subsidiary bank dividend payments. During the year ended December 31, 2024, First Financial Bank paid dividends of $200.0 million to us. In addition, federal bank regulatory agencies have the authority to prohibit First Financial Bank from engaging in unsafe or unsound practices in conducting their business. The payment of dividends or other transfers of funds to us, depending on the financial condition of First Financial Bank, could be deemed an unsafe or unsound practice.

Dividend payments from First Financial Bank would also be prohibited under the "prompt corrective action" regulations of federal bank regulators if First Financial Bank is, or after payment of such dividends would be, undercapitalized under such regulations. In addition, First Financial Bank is subject to restrictions under federal law that limit their ability to transfer funds or other items of value to us and our non-bank subsidiaries, including affiliates, whether in the form of loans and other extensions of credit, investments and asset purchases, or as other transactions involving the transfer of value. Unless an exemption applies, these transactions by First Financial Bank with us are limited to 10% of First Financial Bank's capital stock and surplus and, with respect to all such transactions with affiliates in the aggregate, to 20% of First Financial Bank's capital stock and surplus. As of September 30, 2025, a maximum of approximately $197.4 million was available to us from First Financial Bank pursuant to these limitations. Moreover, loans and extensions of credit by First Financial Bank to its affiliates, including us, generally are required to be secured in specified amounts. A bank's transactions with its non-bank affiliates also are required generally to be on arm's-length terms. Accordingly, we can provide no assurance that we will receive dividends or other distributions from First Financial Bank and our other subsidiaries in an amount sufficient to pay interest on or principal of the subordinated notes.

Holders of the subordinated notes will have limited rights, including limited rights of acceleration, if there is an event of default.

Payment of principal on the subordinated notes may be accelerated only in the case of certain events of bankruptcy or insolvency involving us or First Financial Bank. There is no automatic acceleration, or right of acceleration, in the case of default in the payment of principal of or interest on the subordinated notes, or in the performance of any of our other obligations under the subordinated notes or the Subordinated Indenture governing the subordinated notes. Our regulators can, in the event we or First Financial Bank become subject to an enforcement action, prohibit First Financial Bank from paying dividends to us, and prevent our payment of interest or principal on the subordinated notes and any dividends on our capital stock, but such limits will not permit acceleration of the subordinated notes. See "Description of the Subordinated Notes-Events of Default."

Our indebtedness could adversely affect our financial results and prevent us from fulfilling our obligations under the subordinated notes.

In addition to our currently outstanding indebtedness and any additional indebtedness we may incur pursuant to this offering, we may be able to borrow substantial additional indebtedness, including senior debt, in the future. If new indebtedness is incurred in addition to our current debt levels, the related risks that we now face could increase.

Our indebtedness, including the indebtedness we may incur in the future, could have important consequences for the holders of the subordinated notes, including:

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The Subordinated Indenture does not limit the incurrence of additional indebtedness by us, including secured indebtedness, which would be effectively senior to the subordinated notes to the extent of the value of the collateral securing such indebtedness.

Our business operations may not generate the cash needed to service our indebtedness.

Our ability to make payments on our indebtedness, including the subordinated notes, and to fund planned capital expenditures will depend on our ability to generate cash in the future. We cannot assure you that our business will generate sufficient cash flow from operations or that future borrowings will be available to us in an amount sufficient to enable us to pay interest on and principal of our indebtedness, including the subordinated notes, or to fund our other liquidity needs.

The limited covenants relating to the subordinated notes do not protect you.

The covenants in the Subordinated Indenture governing the subordinated notes are limited. In addition, the subordinated notes and the Subordinated Indenture do not limit our or our subsidiaries' ability to further issue additional subordinated notes, including additional notes of the same series as the subordinated notes, or to incur additional debt. As a result, the terms of the Subordinated Indenture do not protect you in the event of an adverse change in our financial condition or results of operations, and you should not consider the terms of the Subordinated Indenture to be a significant factor in evaluating whether we will be able to comply with our obligations under the subordinated notes.

In addition, we are not restricted under the Subordinated Indenture governing the subordinated notes from granting or incurring a lien on any of our assets, selling or otherwise disposing of any of our assets, paying dividends or issuing or repurchasing our securities including our regular quarterly dividend and any share repurchases pursuant to a share repurchase program. In addition, there are no financial covenants in the Subordinated Indenture governing the subordinated notes. Except as expressly provided in the Subordinated Indenture, you are not protected under the Subordinated Indenture governing the subordinated notes in the event of a highly leveraged transaction, reorganization, default under our existing indebtedness, restructuring, merger or similar transaction that may adversely affect you.

There may be no active market for the subordinated notes.

The subordinated notes are a new issuance of securities with no established trading market. We do not intend to apply for listing of the subordinated notes on any national securities exchange or for quotation of the subordinated notes on any automated dealer quotation system. The underwriters have advised us that they presently intend to make a market in the subordinated notes. However, it is under no obligation to do so and may discontinue any market making activities at any time without any notice. A liquid or active trading market for the subordinated notes may not develop. If an active trading market for the subordinated notes does not develop, the market price and liquidity of the subordinated notes may be adversely affected. If the subordinated notes offered hereby are traded, they may trade at a discount from their initial offering price, depending on prevailing interest rates, the market for similar securities, our performance and other factors.

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If a trading market for the subordinated notes develops, changes in the debt markets, among others, could adversely affect your ability to liquidate your investment in the subordinated notes and the market price of the subordinated notes.

Many factors could affect the trading market for, and the trading value of, the subordinated notes. These factors include: the method of calculating the principal, premium, if any, interest or other amounts payable, if any, on the subordinated notes; the time remaining to the maturity of the subordinated notes; the ranking of the subordinated notes; the redemption features of the subordinated notes; the outstanding amount of subordinated notes with terms identical to the subordinated notes offered hereby; the prevailing interest rates being paid by other companies similar to us; changes in U.S. interest rates; whether the ratings on the subordinated notes or us provided by any rating agency have changed; our financial condition, financial performance and future prospects; the level, direction and volatility of market interest rates generally; general economic conditions of the capital markets in the United States; and geopolitical conditions and other financial, political, regulatory, and judicial events that affect the capital markets generally. The condition of the financial markets and prevailing interest rates have fluctuated significantly in the past and are likely to fluctuate in the future. Such fluctuations could adversely affect the trading market (if any) for, and the market price of, the subordinated notes.

The subordinated notes are not insured or guaranteed by the FDIC, any other governmental agency or instrumentality, or any of our subsidiaries.

The subordinated notes are not savings accounts, deposits or other obligations of First Financial Bank and are not insured by the FDIC or any other governmental agency or instrumentality, or public or private insurer. The subordinated notes are obligations of First Financial only and are neither obligations of, nor guaranteed by, any of our subsidiaries.

Regulatory guidelines may restrict our ability to pay the principal of, and accrued and unpaid interest on, the subordinated notes, regardless of whether we are the subject of an insolvency proceeding.

As a bank holding company, our ability to pay the principal of, and interest on, the subordinated notes is subject to the rules and guidelines of the Federal Reserve regarding capital adequacy. We intend to treat the subordinated notes as "Tier 2 capital" under the Federal Reserve's regulatory rules and guidelines. Pursuant to federal law and the Federal Reserve regulations, as a bank holding company, we are required to act as a source of financial and managerial strength to First Financial Bank and commit resources to its support, including, without limitation, the guarantee of its capital plans if it is undercapitalized. Such support may be required at times when we may not otherwise be inclined or able to provide it. As a result of the foregoing, we may be unable to pay accrued interest on the subordinated notes on one or more of the scheduled interest payment dates, or at any other time, or the principal of the subordinated notes at the maturity of the subordinated notes.

If we were to be the subject of a bankruptcy proceeding under Chapter 11 of the U.S. Bankruptcy Code, then the bankruptcy trustee would be deemed to have assumed and would be required to cure, immediately any deficit under any commitment we have to any of the federal banking agencies to maintain the capital of First Financial Bank, and any other insured depository institution for which we have such a responsibility, and any claim for breach of such obligation would generally have priority over most other unsecured claims.

Our published credit ratings may not reflect all risks of an investment in the subordinated notes. A downgrade in our credit ratings or the ratings of First Financial Bank could have a material adverse impact on us.

The published credit ratings of us or our indebtedness are an assessment by rating agencies of our ability to pay our debts when due. These ratings are not recommendations to purchase, hold or sell the subordinated notes, inasmuch as the ratings do not comment as to market price or suitability for a particular investor, are limited in scope, and do not address all material risks relating to an investment in the subordinated notes, but rather reflect only the view of each rating agency at the time the rating is issued. The published credit ratings assigned to the

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subordinated notes may not reflect the potential impact of all risks related to structure and other factors on any trading market for, or trading value of, the subordinated notes. Accordingly, you should consult your own financial and legal advisors as to the risks entailed by an investment in the subordinated notes and the suitability of investing in the subordinated notes in light of your particular circumstances.

Rating agencies continuously evaluate us and our subsidiaries, and their ratings of our and First Financial Bank's long-term and short-term debt are based on a number of factors, including financial strength, as well as factors not entirely within our and First Financial Bank's control, such as conditions affecting the financial services industry generally. In light of these reviews and the continued focus on the financial services industry generally, we and First Financial Bank may not be able to maintain our current credit ratings. Ratings downgrades by a rating agency could have a significant and immediate impact on our funding and liquidity through cash obligations, reduced funding capacity and collateral triggers. A reduction in our or First Financial Bank's credit ratings could also increase our and First Financial Bank's borrowing costs and limit access to the capital markets.

Downgrades in the credit or financial strength ratings assigned to the counterparties with whom we transact could create the perception that our financial condition will be adversely impacted as a result of potential future defaults by such counterparties. Additionally, we could be adversely affected by a general, negative perception of financial institutions caused by the downgrade of other financial institutions. Accordingly, ratings downgrades for other financial institutions could affect the market price of our stock and could limit our access to or increase our cost of capital.

We will act as the initial calculation agent and may have economic interests adverse to the interests of the holders of the subordinated notes.

The calculation agent will determine the interest rate during the floating rate period. We will act as the initial calculation agent for the subordinated notes. Any exercise of discretion by us under the terms of the subordinated notes, including, without limitation, any discretion exercised by us acting as calculation agent, could present a conflict of interest. In making the required determinations, decisions and elections, we may have economic interests that are adverse to the interests of the holders of the subordinated notes, and those determinations, decisions or elections could have a material adverse effect on the yield on, value of and market for the subordinated notes. Any determination by us, as the calculation agent, will be final and binding absent manifest error.

The subordinated notes may be issued with original issue discount for U.S. federal income tax purposes.

The subordinated notes may be issued with OID for U.S. federal income tax purposes. In such case, holders subject to U.S. federal income taxation, whether on the cash or accrual method of tax accounting, generally would be required to include any amounts representing OID in gross income (as ordinary income) as the OID accrues on a constant yield to maturity basis, in advance of the receipt of cash payments to which such income is attributable. See "Certain U.S. Federal Income Tax Consequences."

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USE OF PROCEEDS

We expect to receive net proceeds from this offering of approximately $    after deducting underwriting discounts and commissions and estimated offering expenses payable by us.

We intend to use the net proceeds from this offering for general corporate purposes, including the potential redemption of our 5.25% Subordinated Notes due 2030.

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CAPITALIZATION

The following table sets forth our consolidated capitalization as of September 30, 2025 (i) on an actual basis and (ii) on an as adjusted basis to give effect to the sale of $    aggregate principal amount of subordinated notes offered hereby and the use of the proceeds therefrom, after deducting the underwriting discount and estimated expenses. The information presented in the following table reflects First Financial's information and does not give effect to the acquisitions of Westfield or BankFinancial. You should read this table in conjunction with the more detailed information, including our consolidated financial statements and related notes, incorporated by reference in this prospectus supplement and accompanying prospectus.

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DESCRIPTION OF SUBORDINATED NOTES

The following summary of the subordinated notes does not purport to be complete and is qualified in its entirety by the Subordinated Indenture (as defined below), including the definitions therein of certain terms. Unless otherwise specified, capitalized terms used in this summary have the meanings specified in the Subordinated Indenture. For purposes of this "Description of Subordinated Notes," references to the "Company," "First Financial," "we," and "us" include only First Financial Bancorp. and not its consolidated subsidiaries.

General

The subordinated notes offered hereby will be issued under a subordinated indenture, dated as of November  , 2025 as amended and supplemented by a first supplemental indenture, to be dated as of the issue date, between First Financial and Wilmington Trust, National Association, as trustee, which together we refer to in this summary as the "Subordinated Indenture."

The subordinated notes will be our general unsecured, subordinated obligations and will rank equal in right of payment and upon our liquidation with any of our existing 5.25% subordinated notes due 2030 and all of our future indebtedness the terms of which provide that such indebtedness ranks equally with the subordinated notes. The subordinated notes will rank junior in right of payment and upon our liquidation to any of our existing and all of our future Senior Indebtedness (as defined in the Subordinated Indenture and described below) to the extent and in the manner set forth in the Subordinated Indenture. In addition, the subordinated notes will be effectively subordinated to all of our secured indebtedness to the extent of the value of the assets securing such indebtedness. The subordinated notes will be structurally subordinated to all of the existing and future liabilities and obligations of our subsidiaries, including the deposit liabilities and claims of other creditors of our subsidiary bank, First Financial Bank. See "-Subordination." The subordinated notes will be obligations of First Financial Bancorp. only and will not be obligations of, and will not be guaranteed by, any of our subsidiaries. The subordinated notes are not deposits and are not insured by the FDIC or any other governmental agency.

The subordinated notes will mature on    , 2035 (the "Maturity Date"), unless previously redeemed or otherwise accelerated. There is no sinking fund for the subordinated notes. We intend for the subordinated notes to qualify (subject to applicable limitations) as Tier 2 capital under applicable capital regulations, guidance, and interpretations of the Board of Governors of the Federal Reserve System (the "Federal Reserve"). Payment of principal on the Notes may be accelerated only in the case of certain events of bankruptcy or insolvency. See "-Events of Default."

Beginning with the interest payment date of    , 2030, and on any interest payment date thereafter, we may, at our option, subject to obtaining the prior approval of the Federal Reserve to the extent such approval is then required under the rules of the Federal Reserve (or, as and if applicable, the rules of any successor appropriate bank regulatory agency) ("Federal Reserve Approval"), redeem the subordinated notes, in whole or in part, at a price equal to 100% of the principal amount of the subordinated notes to be redeemed plus any accrued and unpaid interest to, but excluding, the redemption date. The subordinated notes may not be redeemed by us prior to    , 2030, except that we may, at our option, subject to Federal Reserve Approval, redeem the subordinated notes in whole, but not in part, prior to maturity, including prior to    , 2030, upon the occurrence of a "Tax Event" or a "Tier 2 Capital Event" (as such terms are defined in the Subordinated Indenture) or if we are required to register as an investment company pursuant to the 1940 Act, in each case, at a price equal to 100% of the principal amount of the subordinated notes to be redeemed plus any accrued and unpaid interest to, but excluding, the redemption date. Any partial redemption will be made in accordance with the applicable procedures of The Depository Trust Company (with its successors, "DTC"). See "-Redemption."

We do not intend to apply for the listing of the subordinated notes on any securities exchange or the quotation of the subordinated notes on any quotation system.

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Additional Notes

The subordinated notes will initially be limited to an aggregate principal amount of $    . We may in the future from time to time, without notice to or consent of the holders of the subordinated notes, create and issue additional subordinated notes having the same terms and conditions as the subordinated notes offered by this prospectus supplement in all respects, except for any differences in the issue date and price and interest accrued prior to the issue date of the additional subordinated notes; provided, that no such additional subordinated notes may be issued unless they will be fungible for U.S. securities law purposes and (1) such additional subordinated notes are issued pursuant to a "qualified reopening" of the subordinated notes offered hereby for U.S. federal income tax purposes, or (2) such additional subordinated notes are, and the subordinated notes offered hereby were, issued without OID for U.S. federal income tax purposes; and provided, further, that the additional subordinated notes have the same CUSIP number as the subordinated notes offered hereby. The subordinated notes offered hereby and any additional subordinated notes would rank equally and ratably and would be treated as a single series for all purposes under the Subordinated Indenture. No additional subordinated notes may be issued if any event of default has occurred and is continuing with respect to the subordinated notes.

Interest

From and including the date of original issuance to, but excluding,    , 2030, or the date of earlier redemption (the "fixed rate period"), the subordinated notes will bear interest at an initial rate of    % per annum, payable semi-annually in arrears on    and    of each year (each, a "fixed rate interest payment date"), commencing on     , 2026. The last fixed rate interest payment date for the fixed rate period will be    , 2030.

From and including     , 2030, to, but excluding, the Maturity Date or the date of earlier redemption (the "floating rate period"), the subordinated notes will bear interest at a floating rate per annum equal to the Benchmark rate (which is expected to be Three-Month Term SOFR) plus a spread of    basis points. For each quarterly interest period during the floating rate period, interest will be payable quarterly in arrears on    ,    ,     and    of each year (each, a "floating rate interest payment date" and, together with the fixed rate interest payment dates, the "interest payment dates"), commencing on    , 2031. Notwithstanding the foregoing, if the Benchmark rate is less than zero, the Benchmark rate shall be deemed to be zero.

For the purpose of calculating the interest on the subordinated notes for each interest period during the floating rate period when the Benchmark is Three-Month Term SOFR, "Three-Month Term SOFR" means the rate for Term SOFR for a tenor of three months that is published by the Term SOFR Administrator at the Reference Time for any floating rate period, as determined by the calculation agent after giving effect to the Three-Month Term SOFR Conventions. We will act as the initial calculation agent.

The following definitions apply to the foregoing definition of Three-Month Term SOFR:

"Benchmark" means, initially, Three-Month Term SOFR; provided, that if the calculation agent determines on or prior to the Reference Time for any floating rate interest period that a Benchmark Transition Event and its related Benchmark Replacement Date have occurred with respect to Three-Month Term SOFR or the then-current Benchmark, then "Benchmark" means the applicable Benchmark Replacement for such floating rate interest period and any subsequent floating rate interest periods.

"Corresponding Tenor" means (i) with respect to Term SOFR, three months, and (ii) with respect to a Benchmark Replacement, a tenor (including overnight) having approximately the same length (disregarding business day adjustment) as the applicable tenor for the then-current Benchmark.

"Federal Reserve Bank of New York's Website" means the website of the Federal Reserve Bank of New York ("FRBNY") at http://www.newyorkfed.org, or any successor source. The foregoing Internet website is

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an inactive textual reference only, meaning that the information contained on the website is not part of this prospectus supplement or the accompanying prospectus or incorporated by reference herein or therein.

"Reference Time" with respect to any determination of the Benchmark means (1) if the Benchmark is Three-Month Term SOFR, the time determined by the calculation agent after giving effect to the Three-Month Term SOFR Conventions, and (2) if the Benchmark is not Three-Month Term SOFR, the time determined by the calculation agent after giving effect to the Benchmark Replacement Conforming Changes.

"Relevant Governmental Body" means the Federal Reserve and/or the FRBNY, or a committee officially endorsed or convened by the Federal Reserve and/or the FRBNY or any successor thereto.

"SOFR" means the secured overnight financing rate published by the Federal Reserve Bank of New York, as the administrator of the Benchmark (or any successor administrator), on the Federal Reserve Bank of New York's Website.

"Term SOFR" means the forward-looking term rate for the applicable Corresponding Tenor based on SOFR as published by the Term SOFR Administrator.

"Term SOFR Administrator" means CME Group Benchmark Administration Limited (CBA) (or a successor administrator of Three-Month Term SOFR selected by the calculation agent in its reasonable discretion).

"Three-Month Term SOFR Conventions" means any determination, decision or election with respect to any technical, administrative or operational matter (including with respect to the manner and timing of the publication of Three-Month Term SOFR, or changes to the definition of "interest period," timing and frequency of determining Three-Month Term SOFR with respect to each interest period and making payments of interest, rounding of amounts or tenors, and other administrative matters) that the calculation agent determines may be appropriate to reflect the use of Three-Month Term SOFR as the Benchmark in a manner substantially consistent with market practice (or, if the calculation agent determines that adoption of any portion of such market practice is not administratively feasible or if the calculation agent determines that no market practice for the use of Three-Month Term SOFR exists, in such other manner as the calculation agent determines is reasonably necessary).

The terms "Benchmark Replacement," "Benchmark Replacement Adjustment," "Benchmark Replacement Conforming Changes," "Benchmark Replacement Date" and "Benchmark Transition Event" have the meanings set forth below under the heading "-Effect of Benchmark Transition Event."

Notwithstanding the foregoing paragraphs related to the determination of interest, if the calculation agent determines on or prior to the relevant Reference Time that a Benchmark Transition Event and its related Benchmark Replacement Date (each as defined below) have occurred with respect to Three-Month Term SOFR, then the provisions set forth below under the heading "-Effect of Benchmark Transition Event," which we refer to as the "benchmark transition provisions," will thereafter apply to all determinations of the interest rate on the subordinated notes for each interest period during the floating rate period. In accordance with the benchmark transition provisions, after a Benchmark Transition Event and its related Benchmark Replacement Date have occurred, the interest rate on the subordinated notes for each interest period during the floating rate period will be an annual rate equal to the Benchmark Replacement plus    basis points.

Absent manifest error, the calculation agent's determination of the interest rate for an interest period for the subordinated notes will be binding and conclusive on you, the trustee and us. The calculation agent's determination of any interest rate, and its calculation of interest payments for any period, will be maintained on file at the calculation agent's principal offices, will be made available to any holder of the subordinated notes promptly upon request and will be provided to the trustee.

Interest on the subordinated notes will be calculated on the basis of a 360-day year consisting of twelve 30-day months during the fixed rate period and, during the floating rate period, on the basis of a 360-day year

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and the actual number of days elapsed. Dollar amounts resulting from that calculation will be rounded to the nearest cent, with one-half cent being rounded upward.

Interest on the subordinated notes, subject to certain exceptions, will accrue during the applicable interest period. When we use the term "interest period," we mean the period from and including the immediately preceding interest payment date in respect of which interest has been paid or duly provided for or, if no interest has been paid or duly provided for, from and including the date of issuance of the subordinated notes to, but excluding, the applicable interest payment date or the Maturity Date or date of earlier redemption, if applicable. If a fixed rate interest payment date or the Maturity Date falls on a day that is not a business day, then the interest payment or the payment of principal and interest at maturity will be postponed to the next succeeding business day, but the payments made on such dates will be treated as being made on the date that the payment was first due and the holders of the subordinated notes will not be entitled to any further interest or other payments in respect thereof. However, if a floating rate interest payment date falls on a day that is not a business day, then such floating rate interest payment date will be postponed to the next succeeding business day unless such day falls in the next succeeding calendar month, in which case such floating rate interest payment date will be accelerated to the immediately preceding business day, and, in each such case, the amounts payable on such business day will include interest accrued to, but excluding, such business day.

Interest on each subordinated note will be payable to the person in whose name such subordinated note is registered on the fifteenth day immediately preceding the applicable interest payment date, whether or not such day is a business day. Any interest which is payable, but is not punctually paid or duly provided for, on any interest payment date shall cease to be payable to the holder on the relevant record date by virtue of having been a holder on such date, and such defaulted interest may be paid by us to the person in whose name the subordinated notes are registered at the close of business on a special record date for the payment of defaulted interest. However, interest that is paid on the Maturity Date will be paid to the person to whom the principal is payable. Interest will be payable by wire transfer in immediately available funds in U.S. dollars to DTC or its nominee or, at our option in the event the subordinated notes are not represented by global notes, by check mailed to the address of the person specified for payment in the preceding sentences.

If any of the foregoing provisions concerning the calculation of the interest rate and interest payments during the floating rate period are inconsistent with any of the Three-Month Term SOFR Conventions determined by the calculation agent, then the relevant Three-Month Term SOFR Conventions will apply. Furthermore, if the calculation agent determines that a Benchmark Transition Event and its related Benchmark Replacement Date have occurred with respect to Three-Month Term SOFR at any time when any of the subordinated notes are outstanding, then the foregoing provisions concerning the calculation of the interest rate and interest payments during the floating rate period will be modified in accordance with the benchmark transition provisions.

When we refer to a "business day" with respect to the subordinated notes, we mean any day, other than a Saturday or Sunday, that is neither a federal holiday nor a day on which banking institutions in Cincinnati, Ohio, or New York City or any place of payment are authorized or required by law, regulation or executive order to close; provided, that, when used in connection with an amount that bears interest at a rate based on SOFR or Term SOFR or any direct or indirect calculation or determination of SOFR or Term SOFR, the term "business day" means any such day that is also a U.S. Government Securities Business Day. "U.S. Government Securities Business Day" means any day except for (a) a Saturday, (b) a Sunday or (c) a day on which the Securities Industry and Financial Markets Association recommends that the fixed income departments of its members be closed for the entire day for purposes of trading in United States government securities.

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Ranking

The subordinated notes will be our general unsecured, subordinated obligations. The subordinated notes will not be guaranteed by any of our subsidiaries, including First Financial Bank, which is our principal subsidiary. The subordinated notes will rank:

Subordination

The subordinated notes are junior in right of payment to the prior payment in full of all our Senior Indebtedness. This means that, under certain circumstances where we may not be making payments on all of our debt obligations as they become due, the holders of all of our Senior Indebtedness will be entitled to receive payment in full of all amounts that are due or will become due on their debt securities before the holders of the subordinated notes will be entitled to receive any amounts under the subordinated notes.

The Subordinated Indenture does not restrict us or any of our subsidiaries in any way now or in the future from incurring any debt, whether Senior Indebtedness, secured debt or indebtedness that would be pari passu with or subordinate to the subordinated notes.

The Subordinated Indenture provides that, unless all principal of and any premium or interest on Senior Indebtedness has been paid in full, no payment or other distribution may be made in respect of any subordinated notes under the following circumstances:

If the trustee or any holders of subordinated notes receives any payment or distribution that is prohibited under the subordination provisions, such payment or distribution shall be held in trust for and so paid and

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delivered to the holders of Senior Indebtedness (or their duly authorized representatives) until all Senior Indebtedness shall have been paid in full.

Even if the subordination provisions prevent us from making any payment when due on the subordinated notes, we will be in default on our obligations under the subordinated notes if we do not make the payment when due. This means that the trustee and the holders of subordinated notes can take action against us, but they will not receive any money until the claims of the holders of Senior Indebtedness have been fully satisfied.

The Subordinated Indenture defines "Senior Indebtedness" as:

unless, in any case in the instrument creating or evidencing any such indebtedness or obligation, or pursuant to which the same is outstanding, it is provided that such indebtedness or obligation is not superior in right of payment to the subordinated notes or to other debt that is pari passu with or subordinate to the subordinated notes.

Senior Indebtedness does not include:

As of September 30, 2025, the Company had $27.8 million of Senior Indebtedness outstanding on a consolidated basis.

We are a financial holding company and substantially all of our assets are held by our direct and indirect subsidiaries. We rely on dividends and other payments or distributions from our subsidiaries to pay the interest

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on our debt obligations (such as the subordinated notes offered hereby), which interest expense was $18.4 million and $18.3 million for each of the years ended December 31, 2024 and 2023, respectively (holding company only). Federal and state bank regulations impose certain restrictions on the ability of our bank subsidiaries to pay dividends directly or indirectly to us, to make any extensions of credit to us or certain of our affiliates and to invest in our stock or securities. These regulations also prevent us from borrowing from our bank subsidiaries unless the loans are secured by collateral. Accordingly, we may not have access to sufficient cash to make payments on the subordinated notes. See "Risk Factors."

Because we are a holding company, our rights and the rights of our creditors, including holders of the subordinated notes, to participate in any distribution of assets of any of our subsidiaries upon the liquidation, reorganization, dissolution or winding up of any of our subsidiaries will be structurally subordinated to all existing and future liabilities of such subsidiary and, as such, would be subject to the prior claims of the creditors of such subsidiary (except to the extent that we are a creditor with a recognized claim). In the event of any such distribution of assets of First Financial Bank due in part to its status as an insured depository institution, the claims of its depositors and other general or subordinated creditors would be entitled to priority over claims of its shareholders, including us as its parent holding company and any creditor of ours, such as holders of the subordinated notes. As of September 30, 2025, we had $27.8 million of Senior Indebtedness outstanding on a consolidated basis, and First Financial Bank had $14.4 billion of deposits, $550.0 million of FHLB advances, and $45.2 million of other short term borrowings to which the subordinated notes will be structurally subordinated.

No Additional Amounts

In the event that any payment on the subordinated notes is subject to withholding of any U.S. federal income tax or other tax or assessment (whether as a result of a change in law or otherwise), we will not pay additional amounts with respect to such tax or assessment. For a discussion relating to certain U.S. federal income tax consequences of the ownership and disposition of the subordinated notes, see "Certain U.S. Federal Income Tax Consequences."

Redemption

The subordinated notes are not subject to redemption or prepayment at the option of the holders.

We may, at our option, beginning with the interest payment date of    , 2030, but not prior thereto (except upon the occurrence of certain events specified below), and on any interest payment date thereafter, redeem the subordinated notes, in whole or in part, from time to time, subject to obtaining the Federal Reserve Approval, at a price equal to 100% of the principal amount of the subordinated notes being redeemed plus accrued and unpaid interest to, but excluding, the date of redemption.

In addition, we may, at our option, redeem the subordinated notes, in whole, but not in part, subject to obtaining the Federal Reserve Approval, at a redemption price equal to 100% of the principal amount of the subordinated notes being redeemed plus accrued and unpaid interest to, but excluding, the date of redemption, at any time, including before the Maturity Date, upon the occurrence of:

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The subordinated notes may not otherwise be redeemed prior to the Maturity Date.

In the event of any redemption of the subordinated notes, we will deliver or cause to be delivered a notice of redemption (which notice may be conditional in our discretion on one or more conditions precedent, and the redemption date may be delayed until such time as any or all of such conditions have been satisfied or revoked by us if we determine that such conditions will not be satisfied) to each holder of subordinated notes not less than 10 nor more than 60 days prior to the redemption date. We will provide written notice to the trustee prior to the close of business two Business Days prior to the redemption date (or such shorter period as may be acceptable to the trustee) if any such redemption has been rescinded or delayed, and upon receipt the trustee will provide such notice to each holder of the notes in the same manner in which the notice of redemption was given.

Any partial redemption will be made in accordance with DTC's applicable procedures among all of the holders of the subordinated notes. If any subordinated note is to be redeemed in part only, the notice of redemption relating to such subordinated note shall state the portion of the principal amount thereof to be redeemed. A replacement subordinated note in principal amount equal to the unredeemed portion thereof will be issued in the name of the holder thereof upon cancellation of the original note. The subordinated notes are not subject to redemption or prepayment at the option of the holders.

Events of Default

Under the Subordinated Indenture, an event of default permitting acceleration of the maturity of the subordinated notes will occur with respect to the subordinated notes only upon our or our principal subsidiary bank's bankruptcy, insolvency, liquidation, reorganization or similar event. The term "principal subsidiary bank" means each of (1) any bank subsidiary the consolidated assets of which constitute 40% or more of our consolidated assets and (2) any other bank subsidiary designated as a "principal subsidiary bank" by our Board of Directors; provided, that if the Federal Reserve notifies us that our bank subsidiary that is a principal subsidiary bank applying the tests in clause (1) or (2) above does not qualify as a "major subsidiary depository institution" within the requirements of the Federal Reserve's capital guidelines applicable to bank holding companies, such bank subsidiary will not be a principal subsidiary bank from and after the time we receive from the Federal Reserve such a notice. Currently, First Financial Bank is our only principal subsidiary bank and therefore is a

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"principal subsidiary bank." If an event of default permitting acceleration of the maturity of the subordinated notes occurs and is continuing, either the trustee or the holders of not less than 25% in aggregate principal amount of the outstanding subordinated notes may declare the principal amount and interest to be due and payable immediately. The foregoing provision would, in the event of the bankruptcy or insolvency involving the Company or First Financial Bank, be subject as to enforcement to the broad equity powers of a federal bankruptcy court and to the determination by that court of the nature and status of the payment claims of the holders of the subordinated notes.

If we default in our obligation to pay any interest on the subordinated notes when due and payable and such default continues for a period of 30 days, or if we default in our obligation to pay the principal amount due upon maturity, and such default continues for a period of 30 days, then the trustee may, subject to certain limitations and conditions, seek to enforce its rights and the rights of the holders of subordinated notes of the performance of any covenant or agreement in the Subordinated Indenture. The trustee and holders of the subordinated notes may not accelerate the maturity of the subordinated notes, except upon our or our principal subsidiary bank's bankruptcy, insolvency, liquidation, receivership or similar event.

The Subordinated Indenture also provides that the holders of not less than a majority in principal amount of the subordinated notes may waive any past default with respect to the subordinated notes and its consequences, except a default consisting of:

The Subordinated Indenture contains a provision entitling the trustee to be indemnified by the holders of any outstanding subordinated notes before proceeding to exercise any right or power under the Subordinated Indenture at the holders' request or direction. The holders of a majority in principal amount of outstanding subordinated notes of a series may direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or other power conferred on the trustee, with respect to the subordinated notes of that series. However, the trustee may refuse to follow any direction which is in conflict with any law or the Subordinated Indenture, which may involve the trustee in personal liability or which may be unduly prejudicial to the holders of the subordinated notes not joining in the direction (it being understood that the trustee does not have an affirmative duty to ascertain whether or not any such directions are unduly prejudicial to such holders).

The Subordinated Indenture provides that no holder of the subordinated notes will have any right to institute any proceeding, judicial or otherwise, with respect to the Subordinated Indenture or a subordinated note, or for the appointment of a receiver or trustee, or for any other remedy under the Subordinated Indenture, unless:

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These limitations do not apply to a suit instituted by a holder of subordinated notes for the enforcement of payment of the principal of or interest on the subordinated notes on or after the maturity date.

Modification

Except as set forth below, modification and amendment of the Subordinated Indenture as applicable to the subordinated notes may be made only with the consent of the holders of not less than a majority in principal amount of the subordinated notes and all other series of debt securities issued under the Subordinated Indenture and affected by such modification or amendment (voting as one class).

No modification or amendment of the Subordinated Indenture as applicable to the subordinated notes may, without the consent of each holder affected thereby, do any of the following:

We and the trustee may modify or amend the Subordinated Indenture as applicable to the subordinated notes, without the consent of any holder of the subordinated notes, for any of the following purposes:

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No modification or amendment of the Subordinated Indenture that adversely affects the superior position of any holder of senior indebtedness will be effective against any such holder of senior indebtedness unless such holder of senior indebtedness will have consented to such modification or amendment.

Merger, Consolidation or Sale of Assets

We may consolidate with or merge into any other corporation, or convey or transfer our properties and assets substantially as an entirety to any person or entity; provided, that:

Upon any such consolidation or merger, or conveyance or transfer, the successor corporation formed, or into which we are merged or to which such conveyance or transfer is made, shall succeed to, and be substituted for, us under the Subordinated Indenture, as supplemented.

This covenant would not apply to any recapitalization transaction, change of control of us or a transaction in which we incur a large amount of additional debt unless the transaction or change of control included a merger or consolidation or transfer of all or substantially all of our assets. There are no covenants or other provisions in the Subordinated Indenture providing for a put option or increased interest or that would otherwise afford holders of the subordinated notes additional protection in the event of a recapitalization transaction, a change of control of us or a transaction in which we incur or acquire a large amount of additional debt.

Although there is a limited body of case law interpreting the phrase "substantially as an entirety" and similar phrases, there is no precise established definition of the phrase under applicable law. Accordingly, in certain circumstances, there may be a degree of uncertainty as to whether a particular transaction would involve the property or assets of a person "substantially as an entirety."

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Satisfaction and Discharge

The Subordinated Indenture provides that when, among other things, all subordinated notes not previously delivered to the trustee for cancellation:

and we deposit or cause to be deposited with the trustee as trust funds in trust for such purpose money, in an amount sufficient to pay and discharge the entire indebtedness on the subordinated notes not previously delivered to the trustee for cancellation, for the principal and any premium and interest to the date of such deposit (in the case of subordinated notes which have become due and payable) or to the Maturity Date or the date of redemption, as the case may be;

then, upon our request, the Subordinated Indenture will cease to be of further effect, and we will be deemed to have satisfied and discharged the Subordinated Indenture with respect to the subordinated notes.

Defeasance

Our obligations will be deemed to have been paid and discharged if the following applicable conditions have been satisfied:

Any defeasance of the subordinated notes pursuant to the Subordinated Indenture will be subject to our obtaining the prior approval of the Federal Reserve and any additional requirements that the Federal Reserve may impose with respect to defeasance of the subordinated notes. Notwithstanding the foregoing, if, due to a change in law, regulation or policy subsequent to the issue date of the subordinated notes the Federal Reserve does not require that defeasance of instruments be subject to Federal Reserve approval in order for the instrument to be accorded Tier 2 capital treatment, then no such approval of the Federal Reserve will be required for such defeasance.

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Effect of Benchmark Transition Event

Benchmark Replacement. If the calculation agent determines that a Benchmark Transition Event and its related Benchmark Replacement Date have occurred on or prior to the Reference Time in respect of any interest period during the floating rate period, then the Benchmark Replacement will replace the then-current Benchmark for all purposes relating to the subordinated notes during such interest period and all subsequent interest periods.

Benchmark Replacement Conforming Changes. In connection with the implementation of a Benchmark Replacement, the calculation agent will have the right to make Benchmark Replacement Conforming Changes from time to time.

Certain Defined Terms. As used herein:

"Benchmark Replacement" means the Interpolated Benchmark with respect to the then-current Benchmark, plus the Benchmark Replacement Adjustment for such Benchmark; provided, that if (a) the calculation agent cannot determine the Interpolated Benchmark as of the Benchmark Replacement Date or (b) the then-current Benchmark is Three-Month Term SOFR and a Benchmark Transition Event and its related Benchmark Replacement Date have occurred with respect to Three-Month Term SOFR (in which event no Interpolated Benchmark with respect to Three-Month Term SOFR shall be determined), then

"Benchmark Replacement" means the first alternative set forth in the order below that can be determined by the calculation agent as of the Benchmark Replacement Date:

"Benchmark Replacement Adjustment" means the first alternative set forth in the order below that can be determined by the calculation agent as of the Benchmark Replacement Date:

"Benchmark Replacement Conforming Changes" means, with respect to any Benchmark Replacement, any technical, administrative or operational changes (including changes to the definition of "interest period," timing and frequency of determining rates with respect to each interest period and making payments of interest, rounding of amounts or tenors, and other administrative matters) that the calculation agent determines may be

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appropriate to reflect the adoption of such Benchmark Replacement in a manner substantially consistent with market practice (or, if the calculation agent determines that adoption of any portion of such market practice is not administratively feasible or if the calculation agent determines that no market practice for use of the Benchmark Replacement exists, in such other manner as the calculation agent determines is reasonably necessary).

"Benchmark Replacement Date" means the earliest to occur of the following events with respect to the then-current Benchmark:

If the event giving rise to the Benchmark Replacement Date occurs on the same day as, but earlier than, the Reference Time in respect of any determination, the Benchmark Replacement Date will be deemed to have occurred prior to the Reference Time for such determination.

"Benchmark Transition Event" means the occurrence of one or more of the following events with respect to the then-current Benchmark:

"Compounded SOFR" means the compounded average of SOFRs for the applicable Corresponding Tenor, with the rate, or methodology for this rate, and conventions for this rate (which will be compounded in arrears with a lookback and/or suspension period as a mechanism to determine the interest amount payable prior to the end of each interest period) being established by the calculation agent in accordance with:

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For the avoidance of doubt, the calculation of Compounded SOFR shall exclude the Benchmark Replacement Adjustment and the spread of    basis points per annum.

"Interpolated Benchmark" with respect to the Benchmark means the rate determined by the calculation agent for the Corresponding Tenor by interpolating on a linear basis between: (1) the Benchmark for the longest period (for which the Benchmark is available) that is shorter than the Corresponding Tenor, and (2) the Benchmark for the shortest period (for which the Benchmark is available) that is longer than the Corresponding Tenor.

"ISDA Definitions" means the 2006 ISDA Definitions published by the International Swaps and Derivatives Association, Inc. or any successor thereto, as amended or supplemented from time to time, or any successor definitional booklet for interest rate derivatives published from time to time.

"ISDA Fallback Adjustment" means the spread adjustment (which may be a positive or negative value or zero) that would apply for derivatives transactions referencing the ISDA Definitions to be determined upon the occurrence of an index cessation event with respect to the Benchmark for the applicable tenor.

"ISDA Fallback Rate" means the rate that would apply for derivatives transactions referencing the ISDA Definitions to be effective upon the occurrence of an index cessation date with respect to the Benchmark for the applicable tenor excluding the applicable ISDA Fallback Adjustment.

"Unadjusted Benchmark Replacement" means the Benchmark Replacement excluding the Benchmark Replacement Adjustment.

The terms "Reference Time," "Relevant Governmental Body," "SOFR" and "Term SOFR" have the meanings set forth above under the heading "-Interest."

Determinations and Decisions

We and the calculation agent are expressly authorized to make certain determinations, decisions and elections under the terms of the subordinated notes, including with respect to the use of Three-Month Term SOFR as the Benchmark for the floating rate period and under the benchmark transition provisions. Any determination, decision or election that may be made by us or by the calculation agent under the terms of the subordinated notes, including any determination with respect to the use of Three-Month Term SOFR as the Benchmark for the Floating Rate Period, any determination under the benchmark transition provisions, any determination of a tenor, rate or adjustment or of the occurrence or non-occurrence of an event, circumstance or date and any decision to take or refrain from taking any action or any selection:

Form, Denomination, Transfer, Exchange and Book-Entry Procedures

The subordinated notes offered hereby will be issued only in fully registered form, without interest coupons, and in minimum denominations of $1,000 and integral multiples of $1,000 in excess thereof.

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The subordinated notes offered hereby will be evidenced by a global note which will be deposited with, or on behalf of, DTC, or any successor thereto, and registered in the name of Cede & Co., or Cede, as nominee of DTC. Except as set forth below, record ownership of the global note may be transferred, in whole or in part, only to another nominee of DTC or to a successor of DTC or its nominee.

The global note will not be registered in the name of any person, or exchanged for subordinated notes that are registered in the name of any person, other than DTC or its nominee, unless one of the following occurs:

In those circumstances, DTC will determine in whose names any securities issued in exchange for the global note will be registered. Any such subordinated notes in certificated form will be issued in minimum denominations of $1,000 and multiples of $1,000 in excess thereof and may be transferred or exchanged only in such minimum denominations. In connection with any proposed exchange of a global note for a certificated note, there shall be provided to the trustee all information necessary to allow the trustee to comply with any applicable tax reporting obligations, including, without limitation, any cost basis reporting obligations under Internal Revenue Code Section 6045. The trustee may rely on information provided to it and shall have no responsibility to verify or ensure the accuracy of such information.

DTC or its nominee will be considered the sole owner and holder of the global note for all purposes, and as a result:

The laws of some jurisdictions require that certain kinds of purchasers (for example, certain insurance companies) can only own securities in definitive (certificated) form. These laws may limit your ability to transfer your beneficial interests in the global note to these types of purchasers.

Only institutions (such as a securities broker or dealer) that have accounts with DTC or its nominee (called "participants") and persons that may hold beneficial interests through participants (including through Euroclear Bank SA/NV or Clearstream Banking, société anonyme, as DTC participants) can own a beneficial interest in the global note. The only place where the ownership of beneficial interests in the global note will appear and the only way the transfer of those interests can be made will be on the records kept by DTC (for their participants' interests) and the records kept by those participants (for interests of persons held by participants on their behalf).

Secondary trading in bonds and notes of corporate issuers is generally settled in clearing-house (that is, next-day) funds. In contrast, beneficial interests in a global note usually trade in DTC's same-day funds settlement system, and settle in immediately available funds. We make no representations as to the effect that settlement in immediately available funds will have on trading activity in those beneficial interests.

We will make cash payments of interest on and principal of the global note to Cede & Co., the nominee for DTC, as the registered owner of the global note. We will make these payments by wire transfer of immediately available funds on each payment date.

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You may exchange or transfer the subordinated notes at the corporate trust office of the trustee under the Subordinated Indenture for the series of subordinated notes or at any other office or agency maintained by us for those purposes. We will not require payment of a service charge for any transfer or exchange of the subordinated notes, but First Financial may require payment of a sum sufficient to cover any applicable tax or other governmental charge. The transferor of any note shall provide or cause to be provided to the trustee all information necessary to allow the trustee to comply with any applicable tax reporting obligations, including, without limitation, any cost basis reporting obligations under Internal Revenue Code Section 6045. The trustee may rely on information provided to it and shall have no responsibility to verify or ensure the accuracy of such information.

We have been informed that, with respect to any cash payment of interest on or principal of the global note, DTC's practice is to credit participants' accounts on the payment date with payments in amounts proportionate to their respective beneficial interests in the subordinated notes represented by the global note as shown on DTC's records, unless DTC has reason to believe that it will not receive payment on that payment date. Payments by participants to owners of beneficial interests in subordinated notes represented by the global note held through participants will be the responsibility of those participants, as is now the case with securities held for the accounts of customers registered in "street name."

We also understand that neither DTC nor Cede & Co. will consent or vote with respect to the subordinated notes. We have been advised that under its usual procedures, DTC will mail or send an "omnibus proxy" to us as soon as possible after the record date. The omnibus proxy assigns Cede & Co.'s consenting or voting rights to those participants to whose accounts the subordinated notes are credited on the record date identified in a listing attached to the omnibus proxy.

Because DTC can only act on behalf of participants, who in turn act on behalf of indirect participants, the ability of a person having a beneficial interest in the principal amount represented by the global note to pledge the interest to persons or entities that do not participate in the DTC book-entry system, or otherwise take actions in respect of that interest, may be affected by the lack of a physical certificate evidencing its interest.

DTC has advised us that it will take any action permitted to be taken by a holder of notes (including the presentation of notes for exchange) only at the direction of one or more participants to whose account with DTC interests in the global note are credited and only in respect of such portion of the principal amount of the subordinated notes represented by the global note as to which such participant has, or participants have, given such direction.

DTC has also advised us as follows: DTC is a limited purpose trust company organized under the laws of the State of New York, a "banking organization" within the meaning of the New York Banking Law, a member of the Federal Reserve System, a "clearing corporation" within the meaning of the Uniform Commercial Code, as amended, and a "clearing agency" registered pursuant to the provisions of Section 17A of the Exchange Act. DTC was created to hold securities for its participants and facilitate the clearance and settlement of securities transactions between participants through electronic book-entry changes in accounts of its participants.

Participants include securities brokers and dealers, banks, trust companies and clearing corporations and may include certain other organizations. Certain of such participants (or their representatives), together with other entities, own DTC. Indirect access to the DTC system is available to other entities such as banks, brokers, dealers and trust companies that clear through or maintain a custodial relationship with a participant, either directly or indirectly. The rules applicable to DTC and its direct and indirect participants are on file with the SEC.

The policies and procedures of DTC, which may change periodically, will apply to payments, transfers, exchanges and other matters relating to beneficial interests in the global note. We and the trustee have no responsibility or liability for any aspect of DTC's or any participants' records relating to beneficial interests in the global note, including for payments made on the global note, and we and the trustee are not responsible for maintaining, supervising or reviewing any of those records.

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Calculation Agent

We will appoint a calculation agent for the subordinated notes prior to the commencement of the floating rate period and will keep a record of such appointment at our principal offices, which will be available to any holder of the subordinated notes upon request. In addition, we or an affiliate of ours may assume the duties of the calculation agent. We will act as the initial calculation agent. The trustee will have no responsibility for any act or omission of the calculation agent.

The Trustee

The trustee under the Subordinated Indenture is Wilmington Trust, National Association. If an event of default with respect to the subordinated notes occurs, and is not cured, the trustee will be required to use the degree of care of a prudent person in the conduct of his or her own affairs in the exercise of its powers. Subject to the provisions of the Subordinated Indenture, the trustee will be under no obligation to exercise any of its rights or powers under the Subordinated Indenture at the request of any holders of the subordinated notes, unless they have offered to the trustee security or indemnity satisfactory to the trustee.

Wilmington Trust, National Association in the future, may be the trustee under other indentures pursuant to which we issue debt. Computershare, as successor in interest to Wells Fargo Bank, National Association currently serves as trustee under the indenture governing our 5.25% Subordinated Notes due 2030. Pursuant to the Trust Indenture Act of 1939, if a default occurs with respect to the securities of any series, the trustee will be required to eliminate any conflicting interest as defined in the Trust Indenture Act or resign as trustee with respect to the securities of that series within 90 days of such default, unless such default were cured, duly waived or otherwise eliminated. In the event of such resignation, we would be required to appoint a successor trustee under the Subordinated Indenture for the subordinated notes.

From time to time, we and our subsidiaries may maintain deposit accounts and conduct other banking transactions, including lending transactions, with the trustee in the ordinary course of business. The trustee assumes no responsibility for the accuracy or completeness of the information concerning us or our affiliates or any other party contained in this document or the related documents or for any failure by us or any other party to disclose events that may have occurred and may affect the significance or accuracy of such information.

Payment and Paying Agents

We will pay principal and interest on the subordinated notes at the corporate trust office of the trustee or at such other place that we appoint in accordance with the Subordinated Indenture.

We will pay any interest on the subordinated notes to the registered owner of the subordinated notes at the close of business on the record date for the interest, except in the case of defaulted interest.

Any moneys deposited with the trustee or any paying agent, or then held by us in trust, for the payment of the principal of and interest on any subordinated note that remains unclaimed for two years after the principal or interest has become due and payable will, at our request, be repaid to us, or (if then held by us) be discharged from such trust. After repayment to us, you are entitled to seek payment only from us as an unsecured general creditor.

Governing Law

The Subordinated Indenture and the subordinated notes are governed by and construed in accordance with the laws of the State of New York. The Subordinated Indenture provides that we and the trustee, and each holder of a subordinated note by its acceptance thereof, irrevocably waives, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to the Subordinated Indenture or the subordinated notes, or any transaction contemplated thereby.

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CERTAIN U.S. FEDERAL INCOME TAX CONSEQUENCES

The following is a summary of certain U.S. federal income tax consequences of the acquisition, ownership and disposition of the subordinated notes described in this prospectus supplement. This summary is based upon the provisions of the Internal Revenue Code of 1986, as amended (the "Code"), applicable U.S. Treasury Regulations promulgated thereunder, judicial authorities and administrative interpretations, in each case as of the date of this prospectus supplement, all of which are subject to change or different interpretations, possibly with retroactive effect. We cannot assure you that the U.S. Internal Revenue Service (the "IRS") will not challenge one or more of the tax consequences described in this discussion, and we have not obtained, nor do we intend to obtain, a ruling from the IRS or an opinion of counsel with respect to the U.S. federal income tax consequences of acquiring, owning or disposing of the subordinated notes.

This discussion does not purport to address all U.S. federal income tax consequences that may be relevant to a holder in light of the holder's particular circumstances or status, nor does it discuss the U.S. federal income tax consequences to certain types of holders subject to special treatment under the U.S. federal income tax laws, such as banks and other financial institutions, insurance companies, regulated investment companies, tax-exempt entities, dealers in securities or foreign currency, real estate investment trusts, thrifts, traders in securities that have elected the mark-to-market method of accounting for their securities, partnerships or other pass-through entities (or investors in such entities), U.S. Holders (as defined below) whose "functional currency" is not the U.S. dollar, U.S. Holders that hold subordinated notes through non-U.S. brokers or other non-U.S. intermediaries, persons required to accelerate the recognition of any item of income as a result of such income being included on an applicable financial statement, U.S. expatriates and former long-term residents of the United States or persons that hold the subordinated notes as part of a hedge, wash sale, conversion transaction, straddle or other risk reduction transaction. This discussion is limited to those holders that purchase notes for cash in this offering at their "issue price" (which is the first price at which a substantial amount of the subordinated notes is sold for cash to investors other than to bond houses, brokers or similar persons or organizations acting in the capacity of underwriters, placement agents or wholesalers) and that hold the subordinated notes as capital assets (generally, property held for investment). Moreover, this discussion does not address the effect of any alternative minimum tax, the Medicare tax on investment income, state, local or non-U.S. tax laws or the application of any U.S. federal taxes other than U.S. federal income taxes (such as U.S. federal estate or gift taxes).

If any entity or arrangement that is treated as a partnership for U.S. federal income tax purposes is a holder of subordinated notes, the U.S. federal income tax treatment of a partner in the partnership generally will depend upon the status of the partner and the activities of the partnership. If you are a partnership or a partner in a partnership considering an investment in the subordinated notes, you should consult your own tax advisor about the tax consequences of acquiring, owning and disposing of the subordinated notes.

Investors considering the purchase of subordinated notes should consult their own tax advisors regarding the application of the U.S. federal tax laws to their particular situations and the applicability and effect of state, local or non-U.S. tax laws and tax treaties.

Tax Consequences to U.S. Holders

You are a U.S. Holder for purposes of this discussion if you are a beneficial owner of a subordinated note and, for U.S. federal income tax purposes, you are:

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Payments of Interest and Original Issue Discount

Under applicable Treasury Regulations, a debt instrument will qualify as a "variable rate debt instrument" if (i) its issue price does not exceed the total noncontingent principal payments due under the debt instrument by more than a specified de minimis amount and (ii) the debt instrument provides for stated interest, paid or compounded at least annually, at current values of a single fixed rate and one or more qualified floating rates. We expect that the subordinated notes will meet the requirements for being variable rate debt instruments. We intend to treat the subordinated notes as variable rate debt instruments for U.S. federal income tax purposes. Under this characterization, payments treated as qualified stated interest ("QSI") on the subordinated notes generally will be taxable to you as ordinary income at the time such QSI is received or accrued in accordance with your regular method of accounting for U.S. federal income tax purposes. QSI generally means stated interest that is unconditionally payable in cash at least annually at a single fixed rate, but as discussed below, special rules are applicable to variable rate debt instruments.

The subordinated notes will be treated as issued with OID for U.S. federal income tax purposes if the issue price of the subordinated notes is less than the stated redemption price at maturity by more than a de minimis amount. The stated redemption price at maturity for the subordinated notes is the sum of (i) the principal amount of the subordinated notes and (ii) any interest on the subordinated notes that is not QSI. The issue price of debt instruments equals the first price at which a substantial amount of the debt instruments has been sold (ignoring sales to bond houses, brokers or similar persons or organizations acting in the capacity of underwriters, placement agents or wholesalers). As discussed below, solely for purposes of calculating OID, special rules apply for determining the "maturity" of a subordinated note. If the subordinated notes are issued with OID, a U.S. Holder generally must include such OID in taxable income (as ordinary income) as such OID accrues in accordance with a constant yield method based on a compounding of interest, regardless of the U.S. Holder's regular method of accounting for U.S. federal income tax purposes. Thus, a U.S. Holder generally will be required to include OID in income in advance of the receipt of the cash to which such OID is attributable.

Under applicable Treasury Regulations, to determine the amount of QSI and OID in respect of a variable rate debt instrument, an "equivalent fixed rate debt instrument" must be constructed. The equivalent fixed rate debt instrument of a variable rate debt instrument that has an initial fixed rate followed by one or more qualified floating rates, such as a subordinated note, is constructed as follows: (i) first, the initial fixed rate is replaced with a qualified floating rate such that the fair market value of a subordinated note as of the subordinated note's issue date would be approximately the same as the fair market value of an otherwise identical debt instrument that provides for the replacement qualified floating rate rather than the fixed rate, and (ii) second, each floating rate (including the floating rate determined under clause (i) of this paragraph) is converted into a fixed rate substitute (which, in each case, generally will be the value of each floating rate as of the issue date of the subordinated notes). When the equivalent fixed rate debt instrument has been constructed pursuant to the foregoing rules, the amount of QSI and OID, if any, are determined for the equivalent fixed rate debt instrument by applying the general OID rules to the equivalent fixed rate debt instrument, and a U.S. Holder of subordinated notes will account for such OID, if any, and QSI as if the U.S. Holder held the equivalent fixed rate debt instrument. For each accrual period, appropriate adjustments will be made to the amount of QSI or OID assumed to have been accrued or paid with respect to the equivalent fixed rate debt instrument in the event that such amounts differ from the actual amount of interest accrued or paid on the subordinated notes during the accrual period.

The Treasury Regulations provide special rules for determining the yield and maturity of a debt instrument, such as the subordinated notes, that provide an issuer with the option to redeem the instrument at specified times. The Treasury Regulations generally deem an issuer to exercise a redemption option in a manner that minimizes

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the yield on the debt instrument for purposes of determining whether a debt instrument is issued with OID. Under the terms of the subordinated notes, if the initial fixed rate substitute on the equivalent fixed rate debt instrument (as determined in the manner described above) is less than the fixed rate substitute of the floating rate (as determined in the manner described above), the yield on the subordinated notes will be minimized if the subordinated notes are redeemed immediately before the change in the interest rate on    , 2030, and, therefore, the subordinated notes will be treated as maturing on such date for OID purposes. This assumption is made solely for purposes of determining whether the subordinated notes are issued with OID for U.S. federal income tax purposes and is not an indication of our intention to redeem or not to redeem the subordinated notes at any time. If, contrary to this presumption, the subordinated notes are not redeemed prior to the change in the interest rate on    , 2030, then, solely for OID purposes, the subordinated notes will be deemed to be reissued at their adjusted issue price on the date that they are not redeemed. This deemed reissuance should not result in taxable gain or loss to U.S. Holders.

Based on current market conditions and the manner in which the interest rates on the subordinated notes are determined, we expect that when the foregoing calculations are completed, the subordinated notes will be presumed to remain outstanding until maturity and have no original issue discount or will have de minimis original issue discount that can be disregarded and that, therefore all interest payable on the subordinated notes will be treated as qualified stated interest.

Disposition of the Subordinated Notes.

You generally will recognize capital gain or loss on a sale, redemption, exchange, retirement or other taxable disposition of a subordinated note equal to the difference, if any, between (i) the amount realized on such disposition (excluding amounts attributable to any accrued but unpaid stated interest, which will be taxable as ordinary income to the extent you have not previously included such amounts in income) and (ii) your adjusted tax basis in the subordinated note. The amount realized will equal the sum of any cash and the fair market value of any other property received on the disposition. Your adjusted tax basis in a subordinated note generally will equal the amount you paid for the subordinated note, increased by any OID previously included in your gross income with respect to the subordinated note (including OID accrued in the year of the sale or other disposition). Any such gain or loss will be long-term capital gain or loss if you held the subordinated note for more than one year at the time of the disposition. Long-term capital gains of non-corporate U.S. Holders generally are eligible for reduced rates of taxation. The deductibility of capital losses is subject to limitations.

Information Reporting and Backup Withholding

Payments of stated interest which is QSI, accruals of OID and the proceeds of a disposition (including a retirement or redemption) of subordinated notes may be reported to the IRS. These information reporting requirements, however, do not apply with respect to certain exempt U.S. Holders, such as corporations.

Backup withholding (currently at a rate of 24%) may apply to payments of the foregoing amounts, unless you provide the applicable withholding agent with your taxpayer identification number, certified under penalties of perjury, as well as certain other information, or otherwise establish an exemption from backup withholding.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules will be allowed as a credit against your U.S. federal income tax liability, if any, and may entitle you to a refund, provided the required information is timely furnished to the IRS.

Tax Consequences to Non-U.S. Holders

You are a "Non-U.S. Holder" for purposes of this discussion if you are a beneficial owner of a subordinated note and you are, for U.S. federal income tax purposes, an individual, corporation, estate or trust that is not a U.S. Holder.

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Interest on the Subordinated Notes

Subject to the discussion below under the headings "-Information Reporting and Backup Withholding" and "Foreign Account Tax Compliance Act," payments of interest (which, for purposes of this discussion of Non-U.S. Holders, shall include any OID) on the subordinated notes generally will be exempt from U.S. federal income and withholding tax under the "portfolio interest" exemption if you properly certify as to your non-U.S. status, as described below, and:

The portfolio interest exemption applies only if you appropriately certify as to your non-U.S. status. You generally can meet this certification requirement by providing a properly executed IRS Form W-8BEN or W-8BEN-E, as applicable (or appropriate substitute or successor form) to the applicable withholding agent. If you hold the subordinated notes through a financial institution or other agent acting on your behalf, you may be required to provide appropriate certifications to your agent. Your agent then generally will be required to provide appropriate certifications to the applicable withholding agent, either directly or through other intermediaries.

If you cannot satisfy the requirements described above, payments of interest made to you will be subject to U.S. federal withholding tax, currently at a 30% rate, unless (i) you provide the applicable withholding agent with a properly executed IRS Form W-8BEN or W-8BEN-E, as applicable (or appropriate substitute or successor form) claiming an exemption from (or a reduction of) withholding under an applicable income tax treaty or (ii) the payments of interest are effectively connected with your conduct of a trade or business in the United States and you meet the certification requirements described below (see "-Income or Gain Effectively Connected with a U.S. Trade or Business").

Disposition of the Subordinated Notes

Subject to the discussion below under the headings "-Information Reporting and Backup Withholding" and "Foreign Account Tax Compliance Act," you generally will not be subject to U.S. federal income or withholding tax on any gain realized on a sale, redemption, exchange, retirement or other taxable disposition of a subordinated note (other than amounts attributable to accrued and unpaid interest, which will be treated as described above under "-Interest on the Subordinated Notes") unless:

If you are a Non-U.S. Holder described in the first bullet point above, you generally will be subject to U.S. federal income tax as described below (see "-Income or Gain Effectively Connected with a U.S. Trade or Business"). If you are a Non-U.S. Holder described in the second bullet point above, you generally will be subject to U.S. federal income tax at a flat 30% rate (or a lower applicable income tax treaty rate) on the gain derived from the sale, redemption, exchange, retirement or other taxable disposition, which may be offset by certain U.S.-source capital losses, unless an applicable income tax treaty provides otherwise.

Income or Gain Effectively Connected with a U.S. Trade or Business

If any interest on the subordinated notes or gain from a sale, redemption, exchange, retirement or other taxable disposition of the subordinated notes is effectively connected with a U.S. trade or business conducted by

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you, then you generally will be subject to U.S. federal income tax on such interest or gain on a net income basis in the same manner as a U.S. Holder (unless an applicable income tax treaty provides otherwise). If interest received with respect to the subordinated notes is effectively connected income, the U.S. federal withholding tax described above will not apply (assuming an appropriate certification is provided) unless an applicable income tax treaty provides otherwise. You generally can meet the certification requirements by providing a properly executed IRS Form W-8ECI (or other applicable form) to the applicable withholding agent. In addition, if you are a corporation for U.S. federal income tax purposes, that portion of your earnings and profits that is attributable to such effectively connected income or gain, subject to certain adjustments, may be subject to a "branch profits tax" at a 30% rate (or a lower applicable income tax treaty rate).

Information Reporting and Backup Withholding

Payments to you of interest on a subordinated note, and amounts withheld from such payments, if any, generally will be required to be reported to the IRS and may also be made available to the tax authorities of the country in which you are a tax resident under the provisions of an applicable income tax treaty or agreement. Backup withholding (currently at a rate of 24%) generally will not apply to payments of interest on a subordinated note to a Non-U.S. Holder if the certification described in "-Interest on the Subordinated Notes" above is provided by the Non-U.S. Holder, or the Non-U.S. Holder otherwise establishes an exemption.

Proceeds from a disposition (including a retirement or redemption) of a subordinated note effected by the U.S. office of a U.S. or non-U.S. broker will be subject to information reporting requirements and backup withholding unless you properly certify, under penalties of perjury, as to your non-U.S. status and certain other conditions are met, or you otherwise establish an exemption. Information reporting and backup withholding generally will not apply to any proceeds from a disposition of a subordinated note effected outside the United States by a non-U.S. office of a broker, unless such broker has certain connections to the United States, in which case information reporting, but not backup withholding, will apply unless the broker has documentary evidence in its records that you are a Non-U.S. Holder and certain other conditions are met, or you otherwise establish an exemption.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules will be allowed as a credit against your U.S. federal income tax liability, if any, and may entitle you to a refund, provided the required information is timely furnished to the IRS.

Foreign Account Tax Compliance Act

The Foreign Account Tax Compliance Act imposes a U.S. federal withholding tax (separate and apart from, but without duplication of, the withholding tax described above) at a rate of 30% on payments of interest on, and the gross proceeds from a disposition (including a retirement or redemption) of, a debt instrument paid to certain non-U.S. entities, including certain foreign financial institutions and investment funds (including, in some instances, where such an entity is acting as an intermediary), unless such non-U.S. entity complies with certain withholding and reporting requirements regarding U.S. account holders and U.S. owners of such entity's equity and debt. Pursuant to proposed U.S. Treasury Regulations (upon which taxpayers are permitted to rely until final U.S. Treasury Regulations are issued), this withholding tax generally will not apply to payments of gross disposition proceeds. Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States with respect to these rules may be subject to different rules. Under certain circumstances, a beneficial owner of subordinated notes may be eligible for a refund or credit of such taxes. Prospective purchasers of the subordinated notes should consult their own tax advisors regarding these withholding and reporting provisions.

The preceding discussion of certain U.S. federal income tax consequences is for general information only and is not tax advice. Each prospective investor should consult its own tax advisor regarding the particular U.S. federal, state, local and non-U.S. tax consequences of acquiring, owning and disposing of the subordinated notes, including the consequences of any proposed change in applicable laws.

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CERTAIN ERISA AND BENEFIT PLAN CONSIDERATIONS

A fiduciary of a pension, profit-sharing or other employee benefit plan subject to the U.S. Employee Retirement Income Security Act of 1974, as amended ("ERISA") (each, an "ERISA Plan"), should consider the fiduciary standards of ERISA in the context of the ERISA Plan's particular circumstances before authorizing an investment in the subordinated notes. Among other factors, the fiduciary should consider whether the investment would satisfy the prudence, diversification, delegation of control and conflicts of interest requirements of ERISA, and would be consistent with the documents and instruments governing the ERISA Plan, and whether the investment would involve a prohibited transaction under ERISA or the Code.

In addition, Section 406 of ERISA and Section 4975 of the Code prohibit ERISA Plans, as well as individual retirement accounts and any other plans that are subject to Section 4975 of the Code (together with ERISA Plans, "Plans") from engaging in certain transactions involving "plan assets" with persons who are "parties in interest" under ERISA or "disqualified persons" under the Code with respect to the Plan. A violation of these prohibited transaction rules may result in excise tax or other liabilities under ERISA or the Code for those persons, and the transaction may need to be reversed, unless exemptive relief is available under an applicable statutory, regulatory or administrative exemption.

For example, the acquisition and holding of the subordinated notes or any interest therein by a Plan or any entity whose underlying assets include "plan assets" by reason of any Plan's investment in the entity (a "Plan Asset Entity") with respect to which we, an underwriter or any paying agent, or any of our or its respective affiliates is or becomes a party in interest or disqualified person may result in a prohibited transaction under ERISA or Section 4975 of the Code, unless the subordinated notes (or interests) are acquired and held pursuant to an applicable exemption. The U.S. Department of Labor has issued prohibited transaction class exemptions, or "PTCEs," that may potentially provide exemptive relief if required for direct or indirect prohibited transactions that may arise from the purchase or holding of the subordinated notes, or any interest therein. These exemptions include PTCE 84-14 (for certain transactions determined by independent qualified professional asset managers), PTCE 90-1 (for certain transactions involving insurance company pooled separate accounts), PTCE 91-38 (for certain transactions involving bank collective investment funds), PTCE 95-60 (for transactions involving certain insurance company general accounts), and PTCE 96-23 (for transactions managed by in-house asset managers). In addition, ERISA Section 408(b)(17) and Section 4975(d)(20) of the Code (the "service provider exemption") may provide an exemption for an otherwise prohibited purchase and sale of subordinated notes between a Plan and a party in interest or disqualified person; provided that (i) the issuer of the subordinated notes is not a party in interest or disqualified person with respect to an investing Plan other than by reason of providing services to the Plan or a relationship to a service provider, (ii) neither the issuer of the subordinated notes nor any of its affiliates has or exercises any discretionary authority or control or renders any investment advice with respect to the assets of the Plan involved in the transaction, and provided further that the Plan pays no more and receives no less than "adequate consideration" in connection with the transaction. There can be no assurance that all of the conditions of any such exemption or any other exemption will be satisfied or that any such exemption or other exemption will be available, with respect to any and all possible prohibited transactions that may arise in connection with the acquisition and holding of subordinated notes or interests therein. Fiduciaries of Plans considering an investment in shares in reliance on one or more exemptions should carefully review such exemptions to assure their terms will be satisfied with respect to transactions involving the subordinated notes.

Employee benefit plans that are governmental plans (as defined in Section 3(32) of ERISA), certain church plans (as defined in Section 3(33) of ERISA that have not made an election under Section 410(d) of the Code) and non-U.S. plans (as described in Section 4(b)(4) of ERISA) ("Non-ERISA Arrangements") are not subject to the requirements of Section 406 of ERISA or Section 4975 of the Code but may be subject to similar provisions under applicable federal, state, local, non-U.S. or other laws ("Similar Laws").

Any purchaser or holder of the subordinated notes or any interest therein will be deemed to have represented by its purchase and holding of the subordinated notes or any interest therein that it either (1) is not a Plan, an

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entity deemed to hold the assets of any Plan (a "Plan Asset Entity") or a Non-ERISA Arrangement and is not purchasing or holding the subordinated notes or any interest therein on behalf of or with the assets of any Plan, a Plan Asset Entity or Non-ERISA Arrangement or (2) its purchase, holding and disposition of the subordinated notes, or any interest in the subordinated notes, will not constitute or result in a non-exempt prohibited transaction under ERISA or the Code or a similar violation under any applicable Similar Laws.

The foregoing discussion is merely a summary and should not be construed as legal advice or as complete in all relevant respects.

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Due to the complexity of these rules and the penalties that may be imposed upon persons involved in non-exempt prohibited transactions or other violations, it is important that fiduciaries or other persons considering purchasing the subordinated notes or any interest therein on behalf of or with the assets of any Plan, a Plan Asset Entity or Non-ERISA Arrangement consult with their counsel regarding the potential consequences under ERISA, Section 4975 of the Code or Similar Law, and, if necessary, the availability of exemptive relief under as applicable. Purchasers of the subordinated notes (including interests in a subordinated note) have the exclusive responsibility for ensuring that their purchase and holding of the subordinated notes or any interest therein do not violate the fiduciary or prohibited transaction rules of ERISA or the Code or any Similar Laws. The sale of any subordinated notes or interests therein to a Plan, Plan Asset Entity or Non-ERISA Arrangement is in no respect a recommendation to make such a purchase or a representation by us, the underwriters or any of our or their affiliates or representatives that such an investment meets all relevant legal requirements with respect to investments by any such Plans, Plan Asset Entities or Non-ERISA Arrangements generally or any particular Plan, Plan Asset Entity or Non-ERISA Arrangement or that such investment is appropriate or advisable for such Plans, Plan Asset Entities or Non-ERISA Arrangements generally or any particular Plan, Plan Asset Entity or Non-ERISA Arrangement.

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UNDERWRITING

We have entered into an underwriting agreement, dated     , 2025 (the "Underwriting Agreement"), with Keefe, Bruyette & Woods, Inc. and Janney Montgomery Scott LLC, or the underwriters, with respect to the subordinated notes. Subject to certain conditions, the underwriters have agreed to purchase the aggregate principal amount of subordinated notes set forth next to its name in the following table.

The Underwriting Agreement provides that the obligations of the underwriters to purchase the subordinated notes offered hereby are subject to certain conditions precedent and that the underwriters will purchase all of the subordinated notes if any of the subordinated notes are purchased.

The subordinated notes sold by the underwriters to the public will be offered at the public offering price set forth on the cover of this prospectus supplement. The underwriters may offer the subordinated notes to selected dealers at the public offering price set forth on the cover of this prospectus supplement less a concession not in excess of    % of the principal amount per note. After the initial offering, the underwriters may change the offering price and the other selling terms. The offering of the subordinated notes by the underwriters is subject to receipt and acceptance and subject to the underwriters' right to reject any order in whole or in part.

Discounts, Commission and Expenses

The following table shows the public offering price, the underwriting discounts and commissions that we are to pay the underwriters and the proceeds, before expenses, to us in connection with this offering (expressed as a percentage of the principal amount of the subordinated notes offered hereby).

We estimate expenses payable by us in connection with this offering, other than, in each case, underwriting discounts and commissions, will be approximately $    . This estimate reflects that we may reimburse the underwriters for certain of their reasonable out-of-pocket expenses incurred in connection with their engagement as underwriters, including certain expenses attributable to legal fees and marketing, syndication and travel. The underwriters may also reimburse us for certain of our expenses related to the offering.

Indemnification

We have agreed to indemnify each underwriter, its affiliates, selling agents, employees, officer and directors and each person who controls any underwriter, against certain losses and liabilities, including liabilities under the Securities Act and to contribute to payments that the underwriters may be required to make in respect of these liabilities.

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No Public Trading Markets

There is currently no public trading market for the subordinated notes. In addition, we have not applied and do not intend to apply to list the subordinated notes on any national securities exchange or to have the subordinated notes quoted on an automated dealer quotation system. The underwriters have advised us that it intends to make a market in the subordinated notes. However, the underwriters are not obligated to do so and may discontinue any market-making in the subordinated notes at any time in their sole discretion and without prior notice. Therefore, we cannot assure you that a liquid trading market for the subordinated notes will develop or continue, that you will be able to sell your subordinated notes at a particular time, or that the price that you receive when you sell will be favorable.

No Sale of Similar Securities

We have agreed with the underwriters that for a period of 45 days from the date of the Underwriting Agreement, we and our subsidiaries will not, without the prior consent of the underwriters, offer or sell, or enter into any agreement to sell, any debt securities (excluding deposit obligations) of ours or of our subsidiaries.

Stabilization

In connection with this offering of the subordinated notes, the underwriters may engage in overallotment, stabilizing transactions and syndicate covering transactions. Overallotment involves sales in excess of the offering size, which create a short position for the underwriters. Stabilizing transactions involve bids to purchase the subordinated notes in the open market for the purpose of pegging, fixing or maintaining the price of the subordinated notes. Syndicate covering transactions involve purchases of the subordinated notes in the open market after the distribution has been completed in order to cover short positions. Stabilizing transactions and syndicate covering transactions may cause the price of the subordinated notes to be higher than it would otherwise be in the absence of those transactions. If the underwriters engage in stabilizing or syndicate covering transactions, they may discontinue such activities at any time without notice.

Neither we nor the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of the subordinated notes. In addition, neither we nor any of the underwriters make any representation that the underwriters will engage in these transactions or that these transactions, once commenced, will not be discontinued without notice.

Electronic Distribution

This prospectus supplement and the accompanying prospectus may be made available in electronic format on websites or through other online services maintained by the underwriters or their affiliates.

Other than the prospectus supplement and the accompanying prospectus in electronic format, information on such websites and any information contained in any other website maintained by any of the underwriters or their affiliates is not part of this prospectus supplement or our registration statement of which the related prospectus forms a part, has not been approved or endorsed by us or the underwriters in their capacity as underwriters and should not be relied on by investors.

Our Relationships with the Underwriters

The underwriters and their affiliates have engaged, or may in the future engage, in investment banking transactions, lendings and other commercial dealings in the ordinary course of business with us or our affiliates. The underwriters have received, or may in the future receive, customary fees and commissions for these transactions.

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In addition, in the ordinary course of its business activities, the underwriters and their affiliates may make or hold a broad array of investments and actively trade indebtedness and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own accounts and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. The underwriters and their affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments. Keefe, Bruyette & Woods, Inc. acted as financial advisor to Ohio Farmers with respect to the sale of Westfield to First Financial and Keefe, Bruyette & Woods, Inc. is acting as financial advisor to BankFinancial with respect to its sale to First Financial. Janney Montgomery Scott LLC acted as financial advisor to First Financial with respect to its acquisition of Westfield.

Alternative Settlement Cycle and Other Matters

Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the subordinated notes offered by this prospectus supplement in any jurisdiction in which action for that purpose is required. The subordinated notes offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement, the accompanying prospectus or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. We and the underwriters require that the persons into whose possession this prospectus supplement comes inform themselves about, and observe any restrictions relating to, the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.

We expect that delivery of the subordinated notes will be made against payment therefor on or about     , 2025, which will be the    business day following the date hereof (such settlement being referred to as "T+ "). Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in one business day, unless the parties to any such trade expressly agree otherwise. Accordingly, purchasers who wish to trade the subordinated notes prior to the business day before delivery of the subordinated notes will be required, by virtue of the fact that the subordinated notes initially settle in T+ , to specify an alternate settlement arrangement at the time of any such trade to prevent a failed settlement. Purchasers of the subordinated notes who wish to trade the subordinated notes prior to their date of delivery hereunder should consult their advisors.

Selling Restrictions

European Economic Area

In relation to each member state of the European Economic Area (the "EEA"), each a Member State, no offer of the subordinated notes to the public has been or will be made in that Member State, except that offers of the subordinated notes to the public may be made in that Member State at any time under the following exemptions under the Prospectus Regulation:

provided that no such offer of subordinated notes shall require us or the underwriters to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation.

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For the purposes of the above provisions, the expression "an offer of subordinated notes to the public" in relation to any subordinated notes in any Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any subordinated notes to be offered so as to enable an investor to decide to purchase or subscribe for any subordinated notes, and the expression "Prospectus Regulation" means Regulation (EU) 2017/1129.

United Kingdom

This document is only being distributed to, and is only directed at, persons in the United Kingdom that are qualified investors within the meaning of Article 2(e) of the Prospectus Regulation that are also (i) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended, referred to herein as the Order, and/or (ii) high net worth entities falling within Article 49(2)(a) to (d) of the Order and other persons to whom it may lawfully be communicated. Each such person is referred to herein as a Relevant Person.

In the United Kingdom, any investment or investment activity to which this prospectus supplement relates is available only to Relevant Persons and will only be engaged with Relevant Persons. This prospectus supplement and its contents are confidential and should not be distributed, published or reproduced (in whole or in part) or disclosed by recipients to any other persons in the United Kingdom. Any person in the United Kingdom that is not a Relevant Person should not act or rely on this document or any of its contents.

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LEGAL MATTERS

Certain legal matters in connection with this offering, including the validity of the subordinated notes offered hereby, will be passed upon for us by Squire Patton Boggs (US) LLP, Cincinnati, Ohio. Certain other legal matters in connection with this offering will be passed upon for us by our General Counsel. Certain legal matters in connection with this offering will be passed upon for the underwriters by Skadden, Arps, Slate, Meagher & Flom LLP, New York, New York.

EXPERTS

The consolidated financial statements incorporated in this prospectus supplement by reference to First Financial Bancorp.'s Annual Report on Form 10-K for the year ended December 31, 2024 have been so incorporated in reliance on the report of Crowe LLP, independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

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PROSPECTUS

First Financial Bancorp.

Debt Securities

Common Shares

Preferred Shares

Depositary Shares

Warrants

Rights

Stock Purchase Contracts

Units

The securities listed above may be offered and sold by us from time to time in one or more separate offerings, in amounts, at prices and on other terms to be determined at the time of an offering. We may offer the securities independently or together in any combination for sale directly to purchasers or through underwriters, dealers or agents to be designated at a future date. The specific terms and manner of offering of these securities will be provided in supplements to this prospectus. You should read this prospectus and the applicable prospectus supplement carefully before you invest in the securities described in the applicable prospectus supplement. This prospectus may not be used to consummate sales of securities unless accompanied by a prospectus supplement.

First Financial Bancorp.'s common shares are traded on the NASDAQ Global Select Market under the symbol "FFBC."

You should read this prospectus and any supplements carefully before you invest. Investing in our securities involves risks. See the section entitled "Risk Factors," on page 5 of this prospectus, in the applicable prospectus supplement and the discussion of risk factors contained in our annual and quarterly reports filed with the Securities and Exchange Commission, which are incorporated in this prospectus by reference.

Neither the Securities and Exchange Commission, nor any state securities commission or bank regulatory agency, has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Any securities offered by this prospectus and any accompanying prospectus supplement will be our equity securities or unsecured obligations and will not be deposits or accounts or other obligations of any of our bank or non-bank subsidiaries and are not insured or guaranteed by the Federal Deposit Insurance Corporation, The Board of Governors of the Federal Reserve System or any other governmental or regulatory agency or instrumentality.

The date of this prospectus is November 5, 2025.

TABLE OF CONTENTS

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ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement that we have filed with the Securities and Exchange Commission ("SEC") using a "shelf" registration process. Under this shelf registration statement, we may, from time to time, offer any combination of the securities described in this prospectus in one or more separate offerings.

This prospectus describes the general terms of the securities we may offer and the general manner in which we may offer the securities. Each time we offer securities under this prospectus, we will provide a prospectus supplement that will describe the specific terms of the securities offered and the specific manner in which we will offer the securities. A prospectus supplement may include a discussion of any risk factors or other special considerations applicable to those securities or to us. The prospectus supplement may also add, update or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement, you should rely on the information in the applicable prospectus supplement. You should carefully read both this prospectus and the applicable prospectus supplement, together with the information described under the headings "Where You Can Find More Information" and "Incorporation By Reference," before deciding whether to invest in any of our securities.

You should rely only on the information contained or incorporated by reference in this prospectus and the applicable prospectus supplement. We have not authorized anyone to provide you with additional or different information. If anyone provides you with different, additional or inconsistent information, you should not rely on it. This prospectus is not an offer to sell these securities, and it is not soliciting an offer to buy these securities, in any jurisdiction where it is not permitted. You should not assume that the information in this prospectus or the applicable prospectus supplement or any document incorporated by reference is accurate as of any date other than the dates of the applicable documents.

Unless the context requires otherwise, references to "First Financial Bancorp.," "First Financial," the "Company," "we," "our," "ours" and "us" are to First Financial Bancorp. and its subsidiaries.

Unless otherwise indicated, currency amounts in this prospectus and in any applicable prospectus supplement are stated in United States dollars.

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents incorporated by reference herein may contain forward-looking statements within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. In addition, we may make forward-looking statements orally or in writing to investors, analysts, members of the media, or others. Forward-looking statements reflect our current expectations, estimates or projections concerning future results or events. In some cases, you can identify these statements by forward-looking words such as "may," "might," "will," "should," "expects," "intends," "plans," "anticipates," "believes," "estimates," "predicts," "potential" or "continue," the negative of these terms and other comparable terminology. These forward-looking statements, which are subject to risks, uncertainties and assumptions (some of which are beyond our control and ability to predict), may include projections of our future financial performance, future expenses, anticipated growth strategies, descriptions of new business initiatives and anticipated trends in our business or financial results. These statements are not guarantees of future performance and are only predictions based on our current expectations and projections about future events. Undue reliance should not be placed on forward-looking statements. Among the important factors that could cause the Company's actual financial condition and results of operations, level of activity, performance or achievements to differ materially from those indicated by such forward-looking statements are the factors disclosed under "Risk Factors" in Item 1A of our most recent Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on February 20, 2025, as such factors may be updated from time to time in our periodic filings with the SEC, as well as the other information contained or incorporated by reference in this prospectus. Forward-looking statements speak only as of the date on which such statements are made. Except as required by law, we undertake no obligation to update any forward-looking statement to reflect events or circumstances after the date on which such statement is made, or to reflect the occurrence of unanticipated events.

While no list of assumptions, risks, or uncertainties could be complete, some of the factors that may cause actual results or other future events or circumstances to differ from those in forward-looking statements include:

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Additional factors that may cause our actual results to differ materially from those described in our forward-looking statements can be found in our Form 10-K for the year ended December 31, 2024, as well as our other filings with the SEC, which are available on the SEC website at www.sec.gov. Information contained on any website we refer to in this Registration Statement does not and will not constitute a part of this Registration Statement and such references are intended to be inactive textual references only.

All forward-looking statements included in this filing are made as of the date hereof and are based on information available at the time of the filing. Except as required by law, the Company does not assume any obligation to update any forward-looking statement.

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WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement on Form S-3 that we filed with the SEC registering the securities that may be offered hereunder. As permitted by SEC rules, this prospectus does not contain all of the information we have included in the registration statement. A copy of the registration statement can be obtained at the address set forth below. You should read the registration statement for more information about our securities and us.

We are subject to the reporting requirements of the Exchange Act and file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public at the SEC's website at http://www.sec.gov.

Our website address is www.bankatfirst.com. We make available, free of charge, on or through our website, our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K that are filed with or furnished to the SEC, and amendments to those reports, as soon as reasonably practicable after we electronically file such reports with, or furnish them to, the SEC. The contents of our website are not part of this prospectus, and the reference to our website does not constitute incorporation by reference in this prospectus of the information contained at that website.

INCORPORATION BY REFERENCE

The SEC allows us to "incorporate by reference" information in this prospectus. This means that we can disclose important information to you by referring you to another document filed separately with the SEC. The following documents that we have filed with the SEC are incorporated by reference in, and considered a part of, this prospectus:

We are also incorporating by reference in this prospectus all documents (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) that we file with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus and prior to the termination or completion of any offering of securities under this prospectus and all applicable prospectus supplements.

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We will provide to each person to whom this prospectus is delivered, upon written or oral request and without charge, any of the above documents that are incorporated by reference in this prospectus (including any exhibits that are specifically incorporated by reference in such documents). Requests should be directed to:

First Financial Bancorp.

255 East Fifth Street

Suite 700

Cincinnati, Ohio 45202

Telephone: (877) 322-9530

Attention: Investor Relations

Any statement contained in this prospectus or in a document incorporated by reference in this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in the applicable prospectus supplement or any other subsequently filed document that is deemed to be incorporated by reference in this prospectus modifies or supersedes such statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

FIRST FINANCIAL BANCORP.

First Financial Bancorp. is an $18.6 billion financial holding company headquartered in Cincinnati, Ohio. The Company primarily operates through First Financial Bank, an Ohio-chartered commercial bank with 127 full service banking centers at September 30, 2025. First Financial provides banking and financial services products to business and retail clients through its six lines of business: Commercial, Retail Banking, Mortgage Banking, Wealth Management, Investment Commercial Real Estate and Commercial Finance. The Commercial Finance business lends to targeted industry verticals and has a national geographic footprint. Wealth Management, operating under the brand of Yellow Cardinal Advisory Group, had $4.0 billion in assets under management as of September 30, 2025, and provides the following services: financial planning, investment management, trust administration, estate settlement, business succession planning services, brokerage services and retirement planning.

Our principal executive offices are located at 255 East Fifth Street, Suite 700, Cincinnati, Ohio 45202, and our telephone number is (877) 322-9530. We maintain a website at www.bankatfirst.com where general information about us is available. The information on our website is not a part of, and is not incorporated into, this prospectus or any applicable prospectus supplement.

RISK FACTORS

Investing in our securities involves risk. Before you decide to invest in our securities, you should carefully consider and evaluate all of the information included and incorporated by reference in this prospectus, including the risk factors incorporated herein by reference from our most recent Annual Report on Form 10-K, as updated by our subsequent Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other filings with the SEC, as well as the risk factors set forth under the "Risk Factors" heading in any applicable prospectus supplement. In addition to those risk factors, there may be additional risks and uncertainties of which management is not aware or focused on or that management deems immaterial. It is possible that our business, financial condition, liquidity or results of operations could be materially adversely affected by any of these risks. In addition, see "Forward-Looking Statements" above for a description of certain risks and uncertainties associated with our business. The market or trading price of our securities could decline due to any of these risks and uncertainties, and you may lose all or a part of your investment.

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USE OF PROCEEDS

We intend to use the net proceeds from the sales of the securities that may be offered under this prospectus as set forth in the applicable prospectus supplement.

DESCRIPTION OF DEBT SECURITIES

For purposes of this section, the terms "we," "our" and "us" refer only to First Financial and not its subsidiaries. The following description of the debt securities sets forth certain general terms that may apply to the debt securities that we may offer under this prospectus. The debt securities may be issued as senior debt securities or subordinated debt securities. Unless otherwise specified in the applicable prospectus supplement, we may issue senior debt securities under a senior indenture (the "senior indenture"), which we will enter into with a trustee to be named in the senior indenture. Prior to issuing any debt securities under such senior indenture, we will select the trustee for the senior indenture (the "senior indenture trustee") relating to the issuance of senior debt securities, qualify the senior indenture trustee under the Trust Indenture Act and execute such senior indenture. We also may issue subordinated debt securities in one or more series under the Subordinated Indenture, dated November 5, 2025 (the "subordinated indenture"), between First Financial and Wilmington Trust, National Association ("Wilmington"), and the related supplemental indentures for such subordinated debt securities. Each of the senior indenture trustee and Wilmington is referred to as the "indenture trustee," unless otherwise specified.

The senior indenture and subordinated indenture are sometimes collectively referred to as the "indentures" and individually referred to as an "indenture," and the senior debt securities and the subordinated debt securities are sometimes referred to as the "debt securities." The indentures are subject to and governed by the Trust Indenture Act of 1939, as amended (the "Trust Indenture Act"). The form of senior indenture and the subordinated indenture are incorporated by reference in the registration statement of which this prospectus is a part.

The following summary of the terms of the indentures is subject to, and qualified in its entirety by reference to, the indentures, which contain the full legal text of the matters described in this section, and the description of the specific terms of the debt securities in the applicable prospectus supplement. The following summary is not complete. You should read all of the provisions of the indentures, including the definitions of certain terms.

Since we are a holding company, our right, and accordingly, the right of our creditors and shareholders, including the holders of the securities offered by this prospectus and any prospectus supplement, to participate in any distribution of assets of any of our subsidiaries upon its liquidation, reorganization or similar proceeding is subject to the prior claims of creditors of that subsidiary, except to the extent that our claims as a creditor of the subsidiary may be recognized.

Terms of the Securities

The debt securities will not be secured by any of our assets. All of the debt securities issued under each of the indentures will rank equally and ratably with any additional debt securities issued under the same indenture. The subordinated debt securities will be subordinated as described below under the heading "Subordination."

The indentures give us broad authority to set the particular terms of each series of debt securities, including the right to modify certain of the terms contained in the applicable indenture. We will describe the specific terms of a series of debt securities and the extent, if any, to which the specific terms of the debt securities modify the terms of the applicable indenture in the prospectus supplement relating to the debt securities.

Neither the indentures nor the debt securities limit or otherwise restrict the amounts of other indebtedness that we may incur, or the amount of other securities that we may issue. The indentures do not limit the principal

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amount of any particular series of debt securities. Each prospectus supplement will specify the particular terms of the debt securities being offered, including the following, as may be applicable:

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Some of our debt securities may be issued as "original issue discount" securities. Original issue discount securities bear no interest or bear interest at below-market rates and will be sold at a discount below their stated principal amount. The prospectus supplement will also contain any special tax, accounting or other information relating to original issue discount securities or relating to certain other kinds of securities that may be offered, including securities linked to an index.

Acceleration of Maturity

If an event of default with respect to any outstanding series of debt securities occurs and is continuing, the indenture trustee or the holders of at least 25% in principal amount of the outstanding debt securities of that series may declare the principal amount due and payable immediately by providing written notice of such acceleration to us, and, if notice is given by the holders instead of the indenture trustee, to the indenture trustee. Under the subordinated indenture, all outstanding subordinated debt securities will become immediately due and payable, only upon the following events of default:

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Subject to certain conditions, the declaration of acceleration may be rescinded, and past defaults (except uncured payment defaults and certain other specified defaults) may be waived, by the holders of not less than a majority of the principal amount of debt securities of that series. You should refer to the prospectus supplement relating to each series of debt securities for the particular provisions relating to acceleration of maturity upon the occurrence and continuation of an event of default.

Registration and Transfer

We will issue the subordinated debt securities in registered form only, without coupons.

Each series of senior debt securities will also be issued in registered form only, without coupons, unless otherwise indicated in the applicable prospectus supplement. The senior indenture allows us to issue the securities in bearer form, or in both registered and bearer form. Any securities issued in bearer form will have interest coupons attached, unless they are issued as zero coupon securities. Securities in bearer form will not be offered, sold, resold or delivered in connection with their original issuance in the United States or to any United States person other than to offices of certain United States financial institutions located outside the United States.

Unless otherwise indicated in the applicable prospectus supplement, the debt securities we are offering will be issued in denominations of $1,000 or an integral multiple of $1,000. No service charge will be made for any transfer or exchange of the debt securities, but we may require payment of an amount sufficient to cover any tax or other governmental charge payable in connection with a transfer or exchange.

Payment and Paying Agent

We will pay principal, interest and any premium on fully registered debt securities in the designated currency or currency unit at the office of a designated paying agent. At our option, payment of interest on fully registered debt securities may also be made by check mailed to the persons in whose names the debt securities are registered on the days specified in the indentures or any prospectus supplement.

With respect to senior debt securities issued in bearer form, we will pay principal, interest and any premium on such bearer senior debt securities in the designated currency or currency unit at the office of a designated paying agent or agents outside of the United States. Payments will be made at the offices of the paying agent in the United States only if the designated currency is United States dollars and payment outside of the United States is illegal or effectively precluded. If any amount payable on a debt security or coupon remains unclaimed at the end of two years after such amount became due and payable, the paying agent will release any unclaimed amounts, and the holder of the debt security or coupon will look only to us for payment.

Global Securities

The debt securities of a series may be issued in whole or in part in the form of one or more global certificates ("Global Securities") that will be deposited with a depositary to be identified in the applicable prospectus supplement. Global Securities may be issued in either temporary or permanent form. Global Securities representing subordinated debt securities must be issued in registered form only, whereas Global Securities representing senior debt securities may be issued in registered or bearer form. Global Securities in bearer form will be deposited with a depositary outside the United States. Unless and until it is exchanged in whole or in part for individual certificates evidencing senior debt securities in definitive form represented thereby, a bearer Global Security may not be transferred except as a whole by the depositary to a nominee of that depositary or by a nominee of that depositary to a depositary or another nominee of that depositary.

The specific terms of the depositary arrangements for each series of debt securities will be described in the applicable prospectus supplement.

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Modification and Waiver

Modification with Consent of the Holders

Each indenture provides that modifications and amendments may be made by us and the indenture trustee with the consent of the holders of a majority in principal amount of the outstanding debt securities of each series affected by the amendment or modification. However, no modification or amendment may, without the consent of each holder affected:

In addition to the above, no modification or amendment to the subordinated indenture or the rights of holders of subordinated debt securities may, without the consent of each holder of such subordinated debt securities affected:

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Waiver of Compliance or Default

The holders of a majority in principal amount of the outstanding debt securities of any series may waive compliance by us and the indenture trustee with certain provisions of the indentures. The holders of a majority in principal amount of the outstanding debt securities of any series may waive any past default under the applicable indenture with respect to that series, except a default in the payment of the principal, or any premium, interest, or additional amounts payable on a debt security of that series or in respect of a covenant or provision which under the terms of the applicable indenture cannot be modified or amended, without the consent of each affected holder.

Modification of Senior Debt Securities without Consent

With the senior indenture trustee, we may modify and amend any senior indenture without the consent of any holder of senior debt securities for any of the following purposes:

Modification of Subordinated Debt Securities without Consent

Together with Wilmington, we may modify and amend any subordinated indenture without the consent of any holder of subordinated debt securities for any of the following purposes:

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Calculation of Outstanding Debt Securities

To calculate whether the holders of a sufficient principal amount of the outstanding securities have given any request, demand, authorization, direction, notice, consent or waiver under any indenture:

Additional Provisions

Other than the duty to act with the required standard of care during an event of default, the indenture trustee is not obligated to exercise any of its rights or powers under the applicable indenture at the request or direction of any of the holders of the debt securities, unless the holders have offered the indenture trustee reasonable indemnification. Each indenture provides that the holders of a majority in principal amount of outstanding debt securities of any series may, in certain circumstances, direct the time, method and place of conducting any proceeding for any remedy available to the indenture trustee, or exercising any trust or other power conferred on the indenture trustee.

No holder of a debt security of any series will have the right to institute any proceeding for any remedy under the applicable indenture, unless:

However, the holder of any debt security will have an absolute and unconditional right to receive payment of the principal, any premium, any interest or any additional amounts in respect of such debt security on or after the date expressed in such debt security and to institute suit for the enforcement of any such payment.

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We are required to file annually with the indenture trustee a certificate of no default, or specifying any default that exists.

Conversion Rights for Senior Debt Securities

We will set forth in the applicable prospectus supplement the terms on which senior debt securities of any series may be convertible. The subordinated indenture does not provide for conversion of the subordinated debt securities.

Events of Default

The following will be events of default under the senior indenture with respect to the senior debt securities of a series:

The following will be events of default under the subordinated indenture with respect to the subordinated debt securities of a series unless such event is inapplicable to a particular series or is deleted or modified with respect to such series in the applicable resolution of our Board of Directors or supplemental indenture under which such series is issued:

In the event of a default in the payment of interest or principal, the holders of senior indebtedness will be entitled to be paid in full before any payment can be made to holders of subordinated debt securities. However, a

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holder of a subordinated debt security (or Wilmington or any identified trustee under the applicable subordinated indenture on behalf of all of the holders of the affected series) may, subject to certain limitations and conditions, seek to enforce overdue payments of interest or principal on the subordinated debt securities.

Subordination

The senior debt securities will be unsecured and will rank equally among themselves and with all of our unsubordinated debt or other unsecured debt, if any.

The subordinated debt securities will be unsecured and will be subordinate and junior in right of payment, to the extent and in the manner set forth below, to the prior payment in full of all of the Company's senior indebtedness, as more fully described in the applicable prospectus supplement.

If any of the following circumstances has occurred, payment in full of all principal, premium, if any, and interest must be made or provided for with respect to all outstanding senior indebtedness before we can make any payment or distribution of principal, premium, if any, or interest on the subordinated debt securities:

DESCRIPTION OF CAPITAL STOCK

For purposes of this section, the terms "we," "our" and "us" refer only to First Financial and not its subsidiaries. The following summary describes the material features of our capital stock. This summary is subject to, and qualified in its entirety by reference to, our Amended and Restated Articles of Incorporation, as amended ("Articles"), and our Amended and Restated Regulations, as amended ("Regulations"), each of which is filed as an exhibit to the registration statement of which this prospectus is a part. You should refer to, and read this summary together with, our Articles and Regulations to review all of the terms of our capital stock.

Authorized Capital Stock

Our authorized capital stock consists of 160,000,000 common shares, without par value ("common shares") and 10,000,000 preferred shares, with or without par value as determined by the Board ("preferred shares"). As of November 3, 2025, 104,281,794 of our common shares were issued, 98,529,694 of our common shares were outstanding, 5,752,100 of our common shares were held by us in treasury, and none of our preferred shares were issued or outstanding.

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Common Shares

Holders of our common shares are entitled to:

Holders of our common shares have no preemptive, subscription, preference, redemption, conversion, exchange or cumulative voting rights. The rights, preferences and privileges of the holders of our common shares are subject to, and may be adversely affected by, the rights, preferences and privileges of holders of any preferred shares that we may designate and issue in the future.

Subject to compliance with applicable federal and state securities laws, our common shares may be transferred without any restrictions or limitations. The transfer agent and registrar for our common shares is Computershare.

Our common shares are listed on the NASDAQ Global Select Market under the symbol "FFBC". Our outstanding common shares are, and any common shares that we issue under this prospectus and any applicable prospectus supplement will be, when issued, fully paid and nonassessable.

Preferred Shares

Our Articles authorize the Board to issue, without any further vote or action by our shareholders, subject to certain limitations prescribed by law and the rules and regulations of any stock exchange on which our securities may be listed, up to an aggregate of 10,000,000 preferred shares in one or more series.

Subject to the limitations described in the next paragraph, the Board is also authorized to determine and fix the powers, designations, preferences and relative, participating, optional, conversion and other special rights of each series of preferred shares issued from time to time, and the qualifications, limitations and restrictions thereof, including the designation and authorized number of each series, dividend rights, voting rights, conversion rights, redemption and exchange rights, sinking fund requirements and liquidation rights. The Board may increase or decrease the number of shares of any series of preferred shares before or after the issue of that series, but not below the number of shares of such series then outstanding. If the number of preferred shares of any series is so decreased, the shares constituting such decrease will resume the status of authorized but unissued shares. Under Ohio law, the authority of a board to establish the par value of preferred shares is not settled even if such authority is provided in the corporation's articles. Consequently, our preferred shares will be issued without par value unless the Board determines to issue preferred shares with par value after having been advised by counsel that it has the authority to do so.

The Articles provide that the voting rights of each preferred share are limited to no more than one vote per share when voting as a class with the common shares, and the preferred shares will not vote as a separate class or series except as required by Ohio law. The Board has represented that it will not issue, without prior shareholder approval, any series of preferred shares for any defensive or anti-takeover purpose, for the purpose of implementing a shareholder rights plan, or with features specifically intended to make any attempted acquisition of the Company more difficult or costly.

The Board will fix the powers, designations, preferences and relative, participating, optional, conversion and other special rights of each series of preferred shares that we offer under this prospectus and any applicable

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prospectus supplement, and the qualifications, limitations and restrictions of such series, in a certificate of amendment to our Articles relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or incorporate by reference therein from another report that we file with the SEC, the form of any certificate of amendment to our Articles that describes the terms of the series of preferred shares that we are offering before the issuance of the related series of preferred shares. We will also describe in the applicable prospectus supplement the terms of the series of preferred shares being offered.

The Board may authorize the issuance of preferred shares with voting, conversion or other rights that could adversely affect the voting power or other rights of the holders of our common shares. The issuance of preferred shares could have the effect of decreasing the market price of our common shares, restricting our ability to repurchase outstanding common shares, decreasing the amount of earnings and assets available for distribution to holders of our common shares and creating restrictions upon the payment and amount of dividends and other distributions to holders of our common shares. The issuance of preferred shares also could have the effect of delaying, deterring or preventing a change in control of us without further action by our shareholders. When we issue preferred shares under this prospectus and the applicable prospectus supplement, such preferred shares will be fully paid and nonassessable.

As described below under "Description of Depositary Shares," we may, at our option, with respect to any series of preferred shares, elect to offer fractional interests in preferred shares, and provide for the issuance of depositary receipts representing depositary shares, each of which will represent a fractional interest of a share of a particular series of preferred shares. The fractional interest will be specified in the prospectus supplement relating to a particular series of preferred shares.

The transfer agent for any series of preferred shares that we may offer under this prospectus will be named and described in the prospectus supplement for that series.

Anti-Takeover Effects of Certain Provisions of our Articles of Incorporation and Ohio Law

Our Articles contain certain provisions that make it more difficult to acquire control of us by means of a tender offer, open market purchase, a proxy fight or otherwise. These provisions are designed to encourage persons seeking to acquire control of us to negotiate with our Board. We believe that, as a general rule, the interests of our shareholders would be best served if any change in control results from negotiations with our Board. The following provisions of our Articles and Ohio law might have the effect of delaying, deterring or preventing a change in control of us and would operate only with respect to an extraordinary corporate transaction, such as a merger, reorganization, tender offer, sale or transfer of assets or liquidation involving the Company and certain persons described below.

The Ohio General Corporation Law provides that the approval of two-thirds of the voting power of a corporation is required to effect mergers and similar transactions, to adopt amendments to the articles of incorporation of a corporation and to take certain other significant actions. Although under Ohio law the articles of incorporation of a corporation may permit such actions to be taken by a vote that is less than two-thirds (but not less than a majority), our Articles do not contain such a provision. The two-thirds voting requirement tends to make approval of such matters, including further amendments to the Articles, relatively difficult, and a vote of the holders of in excess of one-third of our outstanding common shares would be sufficient to prevent implementation of any of the corporate actions mentioned above.

Ohio Revised Code Section 1701.831 is a "control share acquisition" statute. The control share acquisition statute basically provides that any person acquiring shares of an "issuing public corporation" (which definition we meet) in any of the following three ownership ranges must seek and obtain shareholder approval of the acquisition transaction that first puts such ownership within each such range: (i) more than 20% but less than 33 /3%; (ii) 33 /3% but not more than 50%; and (iii) more than 50%.

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The purpose of the control share acquisition statute is to give shareholders of Ohio corporations a reasonable opportunity to express their views on a proposed shift in control, thereby reducing the coercion inherent in an unfriendly takeover. The provisions of the control share acquisition statute grant to our shareholders the assurance that they will have adequate time to evaluate the proposal of the acquiring person, that they will be permitted to vote on the issue of authorizing the acquiring person's purchase in the same manner and with the same proxy information that would be available to them if a proposed merger of the Company were before them and, most importantly, that the interests of all shareholders will be taken into account in connection with such vote and the probability will be increased that they will be treated equally regarding the price to be offered for their common shares if the purchase is approved.

The control share acquisition statute applies not only to traditional offers but also to open market purchases, privately negotiated transactions and original issuances by an Ohio corporation, whether friendly or unfriendly. The procedural requirements of the control share acquisition statute could render approval of any control share acquisition difficult because it must be authorized at a special meeting of shareholders, at which a quorum is present, by the affirmative vote of the majority of the voting power represented and by a majority of the portion of such voting power, excluding interested shares. Any corporate defense against persons seeking to acquire control may have the effect of discouraging or preventing offers which some shareholders might find financially attractive. On the other hand, the need on the part of the acquiring person to convince our shareholders of the value and validity of the offer may cause such offer to be more financially attractive in order to gain shareholder approval.

Ohio Revised Code Chapter 1704 is a "merger moratorium" statute. The merger moratorium statute provides that, unless a corporation's articles of incorporation or regulations otherwise provide, an "issuing public corporation" (which definition we meet) may not engage in a "Chapter 1704 transaction" for three years following the date on which a person acquires more than 10% of the voting power in the election of directors of the issuing corporation, unless the Chapter 1704 transaction is approved by the corporation's board of directors prior to such transaction. A person who acquires such voting power is an "interested shareholder," and "Chapter 1704 transactions" involve a broad range of transactions, including mergers, consolidations, combinations, liquidations, recapitalizations and other transactions between an issuing public corporation and an interested shareholder if such transactions involve 5% of the assets or shares of the issuing public corporation or 10% of its earning power. After the initial three year moratorium, Chapter 1704 prohibits such transactions absent approval by disinterested shareholders or the transaction meeting certain statutorily defined fair price provisions. One significant effect of Chapter 1704 is to encourage a person to negotiate with a corporation's board of directors prior to becoming an interested shareholder.

Ohio also has enacted Ohio Revised Code Section 1707.043, which provides that a person who announces a control bid must disgorge profits realized by that person upon the sale of any equity securities within 18 months of the announcement.

In addition, Section 1701.59 of the Ohio Revised Code provides that, in determining what a director reasonably believes to be in the best interests of the corporation, such director may consider, in addition to the interests of the corporation's shareholders, any of the interests of the corporation's employees, suppliers, creditors and customers, the economy of the State of Ohio and the United States, community and societal considerations and the long-term as well as the short-term interests in the corporation and its shareholders, including the possibility that these interests may be best served by the continued independence of the corporation.

The overall effect of these statutes may be to render more difficult or discourage the removal of incumbent management or the assumption of effective control by other persons.

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DESCRIPTION OF DEPOSITARY SHARES

For purposes of this section, the terms "we," "our" and "us" refer only to First Financial and not to its subsidiaries. The following description of the depositary shares representing our preferred shares sets forth certain general terms that may apply to the depositary shares that we may offer under this prospectus. The specific terms of the depositary shares and the related deposit agreement and depositary receipts will be described in the applicable prospectus supplement relating to those depositary shares. We will file forms of the applicable deposit agreement and the depositary receipts as exhibits to the registration statement of which this prospectus is a part or as exhibits to one or more reports that we file with the SEC that are incorporated by reference therein. The specific terms of the depositary shares and the related deposit agreement and depositary receipts as described in the applicable prospectus supplement will supplement and, if applicable, may modify or replace the general terms described in this prospectus.

General

We may, at our option, elect to offer fractional preferred shares, rather than full preferred shares. If we exercise this option, we will issue depositary receipts for depositary shares, each of which will represent a fractional interest of a share of a particular series of preferred shares, as specified in the applicable prospectus supplement. We will deposit with a depositary (the "preferred stock depositary") preferred shares of each series represented by depositary shares and enter into a deposit agreement with the preferred stock depositary and holders from time to time of the depositary receipts issued by the preferred stock depositary which evidence the depositary shares. Subject to the terms of the deposit agreement, each owner of a depositary receipt will be entitled, in proportion to the holder's fractional interest in the preferred shares, to all the rights and preferences of the series of the preferred shares represented by the depositary shares (including dividend, voting, conversion, redemption and liquidation rights). The depositary shares will be evidenced by depositary receipts issued pursuant to the deposit agreement. Depositary receipts will be issued to those persons purchasing the fractional preferred shares in accordance with the terms of the deposit agreement as described in the applicable prospectus supplement.

Dividends and Other Distributions

The preferred stock depositary will distribute all cash dividends or other cash distributions received in respect of the preferred shares underlying the depositary shares to the record holders of depositary receipts in proportion to the number of the depositary receipts owned by the holders. The relevant record date for depositary shares will be the same date as the record date for the preferred shares.

In the event of a distribution other than in cash, the preferred stock depositary will distribute property received by it to the record holders of depositary receipts in proportion to the number of the depositary receipts owned by the holders. If the preferred stock depositary determines that it is not feasible to make such distribution, the preferred stock depositary may, with our approval, adopt another method for the distribution, including selling the property and distributing the net proceeds from the sale to the holders.

If we offer to the holders of a series of preferred shares represented by the depositary shares any rights, preferences or privileges to subscribe for or purchase any securities, or any other rights, preferences or privileges, the preferred stock depositary will make such rights, preferences or privileges available to the record holders of depositary shares either by the issue of warrants representing such rights, preferences or privileges or by such other method as approved by the preferred stock depositary and us. If the preferred stock depositary determines that such action is not lawful or feasible or if it is instructed by a holder that such holder does not want to exercise such rights, preferences or privileges, it may (with our approval in any case when the preferred stock depositary has determined that it is not feasible to make such rights, preferences or privileges available) sell such rights, preferences or privileges and distribute the net proceeds from such sale to the holders of depositary shares entitled to such proceeds.

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Withdrawal

Preferred shares represented by depositary shares may be withdrawn from the depositary arrangement upon surrender of depositary receipts at the principal office of the preferred stock depositary and upon payment of the taxes, charges and fees provided for in the deposit agreement. Subject to the terms of the deposit agreement, the holder of depositary receipts will receive the appropriate number of preferred shares and any money or property represented by such depositary shares. Only whole preferred shares may be withdrawn; if a holder holds an amount of depositary shares in excess of whole preferred shares, the preferred stock depositary will deliver along with the withdrawn preferred shares a new depositary receipt evidencing the excess number of depositary shares. Except as described in the deposit agreement, holders of withdrawn preferred shares will not be entitled to redeposit such preferred shares or to receive depositary shares for such preferred shares.

Redemption

If we redeem preferred shares held by the preferred stock depositary, the preferred stock depositary will concurrently redeem the number of depositary shares representing the preferred shares so redeemed (provided that we have paid the applicable redemption price for the preferred shares to be redeemed plus an amount equal to any accrued and unpaid dividends to the date fixed for redemption). The redemption price per depositary share will be equal to the redemption price and any other amounts per share payable on the preferred shares multiplied by the fraction of a preferred share represented by one depositary share. If fewer than all the outstanding depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or pro rata (as nearly as may be practicable without creating fractional depositary shares) or as otherwise determined by us.

After the date fixed for redemption, depositary shares called for redemption will no longer be deemed to be outstanding and all rights of the holders of depositary shares will cease, except the right to receive the monies payable upon redemption and any money or other property to which the holders of the depositary shares were entitled upon redemption upon surrender to the depositary of the depositary receipts evidencing the depositary shares.

Voting

Upon receipt of notice of any meeting at which the holders of the preferred shares are entitled to vote, the preferred stock depositary will mail the information contained in the notice of meeting to the record holders of the depositary receipts. Each record holder of the depositary receipts on the record date (which will be the same date as the record date for the preferred shares) will be entitled to instruct the preferred stock depositary as to the exercise of the voting rights pertaining to the amount of preferred shares represented by the holder's depositary shares. The preferred stock depositary will vote the amount of preferred shares represented by the depositary shares in accordance with the holder's instructions, and we will agree to take all reasonable action necessary to enable the preferred stock depositary to vote such shares. The preferred stock depositary will abstain from voting the amount of preferred shares represented by the depositary shares for which it does not receive specific instructions from the holders of depositary receipts evidencing the depositary shares.

Liquidation Preference

If we voluntarily or involuntarily liquidate, dissolve or wind up, the holders of depositary receipts will be entitled to the fraction of the liquidation preference accorded each preferred share represented by the depositary shares, as set forth in the applicable prospectus supplement.

Adjustments

Upon any change in par value or liquidation preference, split-up, combination or any other reclassification of the series of preferred shares represented by the depositary shares, or upon any recapitalization,

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reorganization, merger or consolidation affecting us or to which we are a party, the preferred stock depositary may in its discretion, with our approval (not to be unreasonably withheld) and instructions, and in such manner as the preferred stock depositary may deem equitable, treat any securities which are received by the preferred stock depositary in exchange for or upon conversion or in respect of such preferred shares as new deposited securities received in exchange for or upon conversion or in respect of such preferred shares and may make such adjustments in the fraction of an interest represented by one depositary share in one such preferred share as may be necessary to fully reflect the effects of such change. With our approval, the preferred stock depositary may execute and deliver additional depositary receipts, or may call for the surrender of all outstanding depositary receipts to be exchanged for new depositary receipts specifically describing such new deposited securities.

Amendment

We may amend the form of depositary receipt and any provision of the deposit agreement at any time by agreement between us and the preferred stock depositary. However, any amendment that materially and adversely alters the rights of the holders of depositary receipts or that would be materially and adversely inconsistent with the rights granted to the holders of the related preferred shares will not be effective unless the holders of at least two-thirds of the depositary shares evidenced by the depositary receipts then outstanding approve the amendment. No amendment will impair the right, subject to the exceptions set forth in the deposit agreement, of any holder of depositary receipts to surrender any depositary receipt with instructions to deliver to the holder the related preferred shares and all money and other property, if any, represented by the depositary receipt, except in order to comply with law. Every holder of an outstanding depositary receipt at the time any such amendment becomes effective will be deemed, by continuing to hold the receipt, to consent and agree to the amendment and to be bound by the deposit agreement as amended.

Termination

We may terminate the deposit agreement upon not less than 30 days' prior written notice to the preferred stock depositary if a majority of each series of preferred shares affected by the termination consents to the termination. Upon termination, the preferred stock depositary will deliver or make available to each holder of depositary receipts, upon surrender of the depositary receipts held by the holder, the number of whole and/or fractional preferred shares represented by the depositary shares evidenced by the depositary receipts together with any other property held by the preferred stock depositary with respect to the depositary receipt.

In addition, the deposit agreement will automatically terminate if:

Charges of Preferred Stock Depositary

We will pay all transfer and other taxes and governmental charges arising solely from the existence of the deposit agreement. In addition, we will pay the fees and charges of the preferred stock depositary in connection with the initial deposit of the preferred shares, the initial issuance of the depositary shares, any redemption of the preferred shares and all withdrawals of preferred shares by owners of depositary shares. All other transfer, income and other taxes and governmental charges will be at the expense of the holders of depositary receipts. Holders of depositary receipts will also pay such other charges and expenses (i) as are expressly provided in the deposit agreement to be for their accounts and (ii) for any duties requested by the holders to be performed which

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are outside of those expressly provided for in the deposit agreement. If those charges, expenses and taxes have not been paid by the holders of depositary receipts, the preferred stock depositary may refuse to transfer depositary shares or withdraw any preferred shares, withhold dividends and distributions and sell the preferred shares or other property represented by the depositary shares evidenced by the depositary receipts.

Resignation and Removal of Preferred Stock Depositary

The preferred stock depositary may resign at any time by delivering to us notice of its election to resign, and we may at any time remove the preferred stock depositary. Any such resignation or removal will take effect upon our appointment of a successor preferred stock depositary and its acceptance of such appointment. We must appoint a successor preferred stock depositary within 60 days after delivery of the notice of resignation or removal, and any preferred stock depositary must be a bank or trust company having its principal office in the United States and having the requisite combined capital and surplus as set forth in the applicable agreement.

Notices

The preferred stock depositary will forward to holders of depositary receipts any notice, reports and other communications that are delivered to the depositary and that we are required to furnish to the holders of the preferred shares. In addition, the depositary will make available for inspection by holders of depositary receipts at the principal office of the depositary, and at such other places as it may from time to time deem advisable, any reports and communications we deliver to the depositary as the holder of preferred shares.

Limitation of Liability

We will not be liable, nor will the preferred stock depositary be liable, if we or the preferred stock depositary are prevented from or delayed, by law or any circumstances beyond our control, in performing our respective obligations under the deposit agreement. Our obligations and the obligations of the preferred stock depositary under the deposit agreement will be limited to performing our duties in good faith and without negligence (only in the case of any action or inaction in the voting of preferred shares represented by the depositary shares), gross negligence or willful misconduct. We will not be obligated, nor will the preferred stock depositary be obligated, to prosecute or defend any legal proceeding in respect of any depositary receipts, depositary shares or preferred shares represented by depositary shares unless satisfactory indemnity is furnished. We may rely, and the preferred stock depositary may rely, on written advice of counsel or accountants, or information provided by holders of depositary receipts or other persons believed in good faith to be competent to give such information, and on documents reasonably believed to be genuine and signed or presented by a proper party.

DESCRIPTION OF WARRANTS

For purposes of this section, the terms "we," "our" and "us" refer only to First Financial and not to its subsidiaries. The following description of the warrants sets forth general terms that may apply to the warrants that we may offer under this prospectus. The specific terms of any series of warrants and the related warrant agreement (including the form of the warrant certificate) will be described in the applicable prospectus supplement relating to those warrants. We will file the form of the applicable warrant agreement (including the form of the warrant certificate) as an exhibit to the registration statement of which this prospectus is a part or as an exhibit to one or more reports that we file with the SEC that are incorporated by reference therein. The specific terms of any series of warrants and the related warrant agreement (including the form of the warrant certificate) as described in the applicable prospectus supplement will supplement and, if applicable, may modify or replace the general terms described in this prospectus.

We may issue warrants in one or more series to purchase debt securities, common shares, preferred shares, depositary shares or units of two or more of those securities. We may issue warrants independently or together

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with any other securities we offer pursuant to a prospectus supplement, and the warrants may be attached to or separate from such securities. We will issue each series of warrants under a separate warrant agreement that we will enter into with a bank or trust company, as warrant agent. The warrant agent will act solely as our agent in connection with the warrants of such series and will not assume any obligation or relationship of agency for or on behalf of holders or beneficial owners of warrants.

The applicable prospectus supplement will describe the terms of any warrants being offered and the applicable warrant agreement (including the form of the warrant certificate), including the following, as may be applicable: the title of the warrants; the total number of warrants to be issued and currently outstanding, if any; the consideration for which we will issue the warrants, including the applicable currency or currencies; anti-dilution provisions to adjust the number of our common shares or other securities to be delivered upon exercise of the warrants; the designation, number or amount and terms of the underlying securities issuable upon exercise of the warrants; the price at which and the currency or currencies in which investors may purchase the underlying securities purchasable upon exercise of the warrants, and any provisions for changes to or adjustments in the price; the dates on which the right to exercise the warrants will commence and expire; the procedures and conditions relating to the exercise of the warrants; whether the warrants will be in registered or bearer form; information with respect to book-entry registration and transfer procedures, if any; the minimum or maximum amount of warrants which may be exercised at any one time; the designation and terms of the related securities with which the warrants are issued and the number of warrants issued with each such security; the date, if any, on and after which the warrants and securities issued with the warrants will be separately transferable; a discussion of material United States federal income tax considerations; the identity of the warrant agent; and any other terms of the warrants, including terms, procedures, conditions and limitations relating to the exchange, transfer, redemption and exercise of the warrants.

Prior to the exercise of their warrants, holders of warrants exercisable for debt securities will not have any of the rights of holders of the debt securities purchasable upon such exercise and will not be entitled to payments of principal (or premium, if any) or interest, if any, on the debt securities purchasable upon such exercise, or to enforce covenants in the applicable indenture. Prior to the exercise of their warrants, holders of warrants exercisable for our common shares, preferred shares or depositary shares will not have any rights of holders of common shares, preferred shares or depositary shares purchasable upon such exercise, including any rights to vote such shares or to receive any distributions or dividends thereon.

Exercise of Warrants

A warrant will entitle the holder to purchase the securities at the exercise price set forth in, or that will be determinable as described in, the applicable prospectus supplement. Warrants may be exercised at any time prior to the close of business on the expiration date, and in accordance with the procedures, set forth in the applicable prospectus supplement. Upon and after the close of business on the expiration date, unexercised warrants will be void and have no further force, effect or value.

Upon receipt of payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the prospectus supplement, we will, as soon as practicable, forward the securities purchased upon such exercise. If less than all of the warrants represented by the warrant certificate are exercised, we will issue a new warrant certificate for the remaining warrants. Warrant certificates may be exchanged for new warrant certificates of different denominations, and warrants may be exercised at the warrant agent's corporate trust office or any other office indicated in the applicable prospectus supplement.

Enforceability of Rights; Governing Law

The holders of warrants, without the consent of the warrant agent, may, on their own behalf and for their own benefit, enforce, and may institute and maintain any suit, action or proceeding against us to enforce their

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rights to exercise and receive the securities purchasable upon exercise of their warrants. Unless otherwise stated in the applicable prospectus supplement, each issue of warrants and the applicable warrant agreement will be governed by the laws of the State of Ohio.

DESCRIPTION OF RIGHTS

For purpose of this section, the terms "we," "our" and "us" refer only to First Financial and not to its subsidiaries. The following description of the rights sets forth certain general terms that may apply to the rights that we may offer under this prospectus. The specific terms of any rights and the related rights agreement (including the form of rights certificate) will be described in the applicable prospectus supplement relating to those rights. We will file the form of the applicable rights agreement (including the form of rights certificate) as an exhibit to the registration statement of which this prospectus is a part or as an exhibit to one or more reports that we file with the SEC that are incorporated by reference therein. The specific terms of any rights and the related rights agreement (including the form of rights certificate) as described in the applicable prospectus supplement will supplement and, if applicable, may modify or replace the general terms described in this prospectus.

We may issue rights to purchase debt securities, common shares, preferred shares or depositary shares that we may offer to our securityholders. The rights may be issued independently or together with any other securities we offer, and may or may not be transferable by the persons purchasing or receiving the rights. In connection with any rights offering, we may enter into a standby underwriting or other arrangement with one or more underwriters or other persons pursuant to which such underwriters or other persons may be required to purchase any offered securities remaining unsubscribed for after such rights offering. Each series of rights will be issued under a separate rights agreement which we will enter into with a bank or trust company, as rights agent, that we will name in the applicable prospectus supplement. The rights agent will act solely as our agent in connection with the certificates representing the rights and will not assume any obligation or relationship of agency or trust for or with any holders of rights certificates or beneficial owners of rights.

The applicable prospectus supplement will describe the terms of any rights being offered and the applicable rights agreement (including the form of the rights certificate), including the following, as may be applicable: the date of determining the securityholders entitled to participate in the rights offering; the consideration for which we will issue the rights; the total number of rights to be issued; the designation, number or amount and terms of the underlying securities issuable upon exercise of the rights; the price at which and the currency or currencies in which investors may purchase the underlying securities purchasable upon exercise of rights, and any provisions for changes to or adjustments in the price; the dates on which the holder's ability to exercise the rights will commence and expire; the procedures and conditions relating to the exercise of the rights; the extent to which the rights will be transferable; the extent to which the rights may include an over-subscription privilege with respect to unsubscribed securities; the material terms of any standby underwriting or purchase agreement entered into by us in connection with the rights offering; a discussion of material United States federal income tax considerations applicable to the exercise of the rights; the identity of the rights agent; and any other terms of the rights, including terms, procedures, conditions and limitations relating to the distribution, exchange and exercise of the rights.

Exercise Price

Each right will entitle its holder to purchase the underlying securities at the exercise price set forth in the applicable prospectus supplement. Our Board will determine the exercise price or prices for the rights based upon a number of factors, including, without limitation: our business prospects; our capital requirements; the price or prices at which an underwriter or standby purchasers may be willing to purchase securities that remain unsold in the rights offering; and general conditions in the securities markets, especially for securities of financial institutions. The subscription price may or may not reflect the actual or long-term fair value of the securities

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offered in the rights offering. We provide no assurances as to the market values or liquidity of any rights issued, or as to whether or not the market prices of the securities subject to the rights will be more or less than the rights' exercise price during the term of the rights or after the rights expire.

Exercising Rights

The manner of exercising rights will be set forth in the applicable prospectus supplement. Upon receipt of payment and the rights certificate properly completed and duly executed at the corporate trust office of the rights agent or any other office indicated in the prospectus supplement, we will, as soon as practicable, forward the securities purchased upon such exercise. If less than all of the rights issued in any rights offering are exercised, we may offer any unsubscribed securities directly to persons other than our securityholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby arrangements, as described in the applicable prospectus supplement.

Expiration of Rights

The applicable prospectus supplement will set forth the expiration date and time for exercising rights. If holders of rights do not exercise their rights prior to such time, their rights will expire and will no longer be exercisable and will become void and have no value. We will extend the expiration date as required by applicable law and may, in our sole discretion, extend the expiration date. If we elect to extend the expiration date, we will issue a press release announcing such extension prior to the scheduled expiration date.

Fees and Expenses

We will pay all fees charged by the rights agent in connection with the distribution and exercise of rights. Rights holders will be responsible for paying all other commissions, fees, taxes or other expenses incurred in connection with their transfer of rights that are transferable. Neither we nor the rights agent will pay such expenses.

Withdrawal and Termination

We may withdraw the rights offering at any time prior to the Expiration Date for any reason. We may terminate the rights offering, in whole or in part, at any time before completion of the rights offering if there is any judgment, order, decree, injunction, statute, law or regulation entered, enacted, amended or held to be applicable to the rights offering that in the sole judgment of our Board would or might make the rights offering or its completion, whether in whole or in part, illegal or otherwise restrict or prohibit completion of the rights offering. We may waive any of these conditions and choose to proceed with the rights offering even if one or more of these events occur. If we terminate the rights offering, in whole or in part, all affected rights will expire without value, and all subscription payments received by the subscription agent will be returned promptly without interest.

DESCRIPTION OF STOCK PURCHASE CONTRACTS

For purpose of this section, the terms "we," "our" and "us" refer only to First Financial and not to its subsidiaries. The following description of stock purchase contracts sets forth certain general terms that may apply to the stock purchase contracts that we may offer under this prospectus. The specific terms of any stock purchase contracts will be described in the applicable prospectus supplement relating to the stock purchase contracts. We will file forms of the relevant documents as exhibits to the registration statement of which this prospectus is a part or as exhibits to one or more reports that we file with the SEC that are incorporated by reference therein. The specific terms of any stock purchase contracts as described in the applicable prospectus supplement will supplement and, if applicable, may modify or replace the general terms described in this prospectus.

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We may issue stock purchase contracts representing contracts obligating holders to purchase from us, and obligating us to sell to the holders, a specified number of common shares, preferred shares or depositary shares at a future date or dates. The price per common share, preferred share or depositary share may be fixed at the time the stock purchase contracts are issued or may be determined by reference to a specific formula set forth in the stock purchase contracts. Any purchase contract may include anti-dilution provisions to adjust the number of shares issuable pursuant to such purchase contract upon the occurrence of certain events.

DESCRIPTION OF UNITS

For purpose of this section, the terms "we," "our" and "us" refer only to First Financial and not to its subsidiaries. We may issue units consisting of one or more debt securities, common shares, preferred shares, depositary shares, warrants, rights, stock purchase contracts or any combination of such securities. The applicable prospectus supplement will describe the terms of any units being offered and the applicable unit agreement (including the form of unit), including the following, as may be applicable: the terms of the units and of the debt securities, common shares, preferred shares, depositary shares, warrants, rights, stock purchase contracts or any combination of such securities comprising the units, including whether and under what circumstances the securities comprising the units may be traded separately; a discussion of material United States federal income tax considerations applicable to the units; and the provisions for the payment, settlement, transfer or exchange or the units.

PLAN OF DISTRIBUTION

We may sell the securities offered under this prospectus from time to time:

The securities we distribute by any of these methods may be sold, in one or more transactions:

Each time we offer securities under this prospectus, the applicable prospectus supplement will describe the specific plan of distribution and the terms of the offering of the securities, including:

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We may sell securities from time to time to one or more underwriters, who would purchase the securities as principal for resale to the public, either on a firm-commitment or best-efforts basis. If we sell securities to underwriters, we will execute an underwriting agreement with the underwriters at the time of sale, and we will name the underwriters in the applicable prospectus supplement. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. The underwriters may resell the securities from time to time in one or more transactions, including negotiated transactions. The underwriters may sell the securities in order to facilitate transactions in any of our other securities (described in this prospectus or otherwise), including other public or private transactions and short sales. The underwriters may offer securities to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more firms acting as underwriters. The underwriters may change from time to time any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers.

In connection with sales to underwriters, the underwriters may be deemed to have received compensation from us in the form of underwriting discounts or commissions and may also receive commissions from purchasers of the securities for whom they may act as agents. Underwriters may resell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from purchasers for whom they may act as agents. The applicable prospectus supplement will include any required information about underwriting compensation we pay to underwriters, and any discounts, concessions or commissions underwriters allow to participating dealers, in connection with an offering of securities.

From time to time, we may sell securities to one or more dealers acting as principals. The dealers, who may be deemed to be underwriters within the meaning of the Securities Act, may then resell those securities to the public. The applicable prospectus supplement will include the names of the dealers and the terms of the transaction.

We may solicit offers to purchase securities directly from the public from time to time. In this case, no underwriters or agents would be involved. We may also designate agents from time to time to solicit offers to purchase securities from the public on our behalf. Such agents may be deemed to be underwriters within the meaning of the Securities Act. The applicable prospectus supplement relating to any particular offering of securities will name any agents designated to solicit offers and will include information about any compensation we may pay the agents in connection with that offering. Unless otherwise indicated in the applicable prospectus supplement, any agent will agree to use its reasonable best efforts to solicit purchases for the period of its appointment.

We may sell the securities directly to institutional investors or others. These persons may be deemed to be underwriters within the meaning of the Securities Act with respect to any sale of those securities. The terms of any such direct sales will be described in the applicable prospectus supplement.

We may make direct sales of the securities through subscription rights distributed to our existing securityholders on a pro rata basis, which may or may not be transferable. In any distribution of subscription

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rights, if all of the underlying securities are not subscribed for, we may then sell the unsubscribed securities directly to third parties or we may engage the services of one or more underwriters, dealers or agents, including standby underwriters, to sell the unsubscribed securities to third parties. The terms of any such sales or arrangements will be described in the applicable prospectus supplement.

We may authorize underwriters, dealers and agents to solicit from certain types of institutional investors offers to purchase securities under delayed delivery contracts providing for payment and delivery on future dates. The applicable prospectus supplement will describe the material terms of these contracts, including any conditions to the purchasers' obligations, and will include any required information about commissions we may pay for soliciting these contracts.

We may authorize one or more "remarketing firms" to sell securities pursuant to a remarketing arrangement upon the purchase of the securities. Remarketing firms will act as principals for their own accounts or as agents for us, and will offer or sell the securities in accordance with a redemption or repayment pursuant to the terms of the securities, or otherwise. The applicable prospectus supplement will identify any remarketing firm and describe the terms of its compensation and agreements, if any, with us. Remarketing firms may be deemed to be underwriters within the meaning of the Securities Act with respect to the securities they remarket.

Unless the applicable prospectus supplement states otherwise, the securities offered under this prospectus (other than our common shares) will be a new issue of securities with no established trading market. We may elect to list any series of offered securities on an exchange. Any underwriters that we use in the sale of offered securities may make a market in such securities, but may discontinue such market making at any time without notice. Therefore, we cannot assure you that the securities will have a liquid trading market.

Any underwriters that we use in the sale of offered securities may engage in over-allotment, stabilizing transactions, syndicate covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions involve bids to purchase the underlying securities in the open market for the purpose of pegging, fixing or maintaining the price of the securities. Syndicate covering transactions involve purchases of the securities, either through exercise of the over-allotment option or in the open market after the distribution has been completed, in order to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a syndicate member when the securities originally sold by the syndicate member are purchased in a syndicate covering transaction to cover short positions. These activities may cause the price of the securities to be higher than it would be in the absence of the transactions. The underwriters may, if they commence these transactions, discontinue them at any time.

Any underwriters, dealers or agents participating in the distribution of the offered securities may be deemed to be underwriters under the Securities Act, and any compensation and profits received by such persons upon sale of the securities may be deemed to be underwriting discounts and commissions under the Securities Act. Underwriters, dealers, agents and other persons may be entitled, under agreements that they may enter into with us, to indemnification by us against certain liabilities, including liabilities under the Securities Act, or to contribution with respect to payments that such persons make with respect to these liabilities. Our underwriters, dealers and agents, or their affiliates, may be customers of, engage in transactions with, or perform services for, us in the ordinary course of business.

VALIDITY OF SECURITIES

Unless otherwise indicated in the applicable prospectus supplement, the validity of the securities being offered under this prospectus will be passed upon for us by Squire Patton Boggs (US) LLP, Cincinnati, Ohio. If the securities are being distributed in an underwritten offering, the validity of the securities will be passed upon for the underwriters by counsel identified in the applicable prospectus supplement.

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EXPERTS

The consolidated financial statements incorporated in this prospectus by reference to First Financial Bancorp's Annual Report on Form 10-K for the year ended December 31, 2024 have been so incorporated in reliance on the report of Crowe LLP, independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

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$    

% Fixed-to-Floating Rate Subordinated Notes due 2035

Prospectus Supplement

Joint Book-Running Managers

The date of this prospectus supplement is November     , 2025.