Supplemental Prospectus (Form 424B3)

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Filed Pursuant to Rule 424(b)(3)

Registration No. 333-288970

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$100,000,000

Common Stock

Warrants

Subscription Rights

Units

We may offer, issue and sell from time to time together or separately, in one or more offerings, any combination of (i) our common stock, (ii) warrants, (iii) subscription rights, and (iv) units. The warrants and subscription rights may be convertible into, or exercisable or exchangeable for, our common stock. The units may consist of any combination of the securities listed above. We may also offer securities as may be issuable upon conversion, redemption, repurchase, exchange or exercise of any securities registered hereunder, including any applicable antidilution provisions.

The aggregate public offering price of the securities that we may offer will not exceed $100,000,000. We will offer the securities in an amount and on terms that market conditions will determine at the time of the offering. Our common stock is currently quoted on the OTCQB tier of OTC Markets Group, Inc. under the symbol "CYDY." On July 24, 2025 the closing price of our common stock was $0.29 per share. You are urged to obtain current market quotations for our common stock. We have no preferred stock, warrants, subscription rights, or units listed on any market. Each prospectus supplement will indicate if the securities offered thereby will be listed or quoted on any securities exchange or another nationally recognized trading market.

Investing in our securities involves risk. You should carefully consider the risks that we have described under the section captioned "Risk Factors" in this prospectus on page 4 before buying our securities.

Should we offer any of the securities described in this prospectus, we will provide you with the specific terms of the particular securities being offered in supplements to this prospectus. You should read this prospectus and any supplement, together with additional information described under the headings "Where You Can Find More Information" and "Incorporation of Certain Information by Reference" carefully before you invest. This prospectus may not be used to sell securities unless accompanied by a prospectus supplement.

We may sell these securities directly to our stockholders or to other purchasers or through agents on our behalf or through underwriters or dealers as designated from time to time, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section titled "Plan of Distribution" in this prospectus and any applicable prospectus supplement. If any agents or underwriters are involved in the sale of any of these securities, the applicable prospectus supplement will provide the names of the agents or underwriters and any applicable fees, commissions, discounts, or over-allotment options will be set forth in a supplement to this prospectus. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a supplement to this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is September 29, 2025

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, using a "shelf" registration process. Under this shelf registration process, we may from time to time offer and sell, in one or more offerings, any or all of the securities described in this prospectus, separately or together, up to an aggregate offering price of $100,000,000. This prospectus provides you with a general description of the securities we may offer. When we issue securities pursuant to this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with additional information described under the heading "Where You Can Find More Information" and "Incorporation of Certain Information by Reference."

CytoDyn Inc. and its consolidated subsidiaries are referred to herein as "CytoDyn," "the Company," "we," "us" and "our," unless the context indicates otherwise.

You may only rely on the information contained in or incorporated by reference in this prospectus, and any accompanying prospectus supplement or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We have not authorized anyone to provide you with different information. This prospectus and any prospectus supplement do not constitute an offer to sell or a solicitation of an offer to buy any securities other than the securities offered by this prospectus or such accompanying prospectus supplement. This prospectus and any prospectus supplement do not constitute an offer to sell or a solicitation of an offer to buy any securities in any circumstances in which such offer or solicitation is unlawful. Neither the delivery of this prospectus or any prospectus supplement nor any sale made hereunder shall, under any circumstances, create any implication that there has been no change in our affairs since the date of this prospectus or such prospectus supplement or that the information incorporated by reference to this prospectus or any prospectus supplement is correct as of any time after its date.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains certain forward-looking statements that involve risks, uncertainties and assumptions that are difficult to predict. Words and expressions reflecting optimism, satisfaction, or disappointment with current prospects, as well as words such as "believes," "intends," "estimates," "expects," "projects," "plans," "anticipates" and variations thereof, or the use of future tense, identify forward-looking statements, but their absence does not mean that a statement is not forward-looking. Our forward-looking statements are not guarantees of performance, and actual results could vary materially from those contained in or expressed by such statements. In evaluating all such statements, we urge you to specifically consider various risk factors identified in this annual report, including the matters set forth under the heading Risk Factors, any of which could cause actual results to differ materially from those indicated by our forward-looking statements.

Our forward-looking statements reflect our current views with respect to future events and are based on currently available financial, economic, scientific, and competitive data and information about current business plans. Forward-looking statements include, among others, statements about leronlimab, its ability to have positive health outcomes, the Company's ability to implement a successful operating strategy for the development of leronlimab and thereby create shareholder value, the ability to obtain regulatory approval of the Company's drug products for commercial sales, and the strength of the Company's leadership team. The Company's forward-looking statements are not guarantees of performance, and actual results could vary materially from those contained in or expressed by such statements due to risks and uncertainties, including: (i) the regulatory determinations of leronlimab's safety and effectiveness to treat the disease and conditions for which we are studying the product by the U.S. Food and Drug Administration (the "FDA") and, potentially, drug regulatory agencies in other countries; (ii) the Company's ability to raise additional capital to fund its operations; (iii) the Company's ability to meet its debt and other payment obligations; (iv) the Company's ability to recruit and retain key employees; (v) the Company's ability to enter into or maintain partnership or licensing arrangements with third parties; (vi) the timely and sufficient development, through internal resources or third-party consultants, of analyses of the data generated from the Company's clinical trials required by the FDA or other regulatory agencies in connection with applications for approval of the Company's drug product; (vii) the Company's ability to achieve approval of a marketable product; (viii) the design, implementation and conduct of clinical trials; (ix) the results of any such clinical trials, including the possibility of unfavorable clinical trial results; (x) the market for, and marketability of, any product that is approved; (xi) the existence or development of vaccines, drugs, or other treatments that are viewed by medical professionals or patients as superior to the Company's products; (xii) regulatory initiatives, compliance with governmental regulations, and the regulatory approval process; (xiii) legal proceedings, investigations, or inquiries affecting the Company or its products; (xiv) general economic and business conditions; (xv) changes in domestic and foreign political and social conditions; (xvi) stockholder actions or proposals with regard to the Company, its management, or its Board of Directors; and (xvii) various other matters, many of which are beyond the Company's control. Should one or more of these risks or uncertainties develop, or should underlying assumptions prove to be incorrect, actual results may vary materially and adversely from those anticipated, believed, estimated, or otherwise indicated by our forward-looking statements. We urge you to specifically consider the various risk factors identified in this prospectus, including the statements set forth in the section titled "Risk Factors" on page 4 and elsewhere in this prospectus, in any accompanying prospectus supplement, and in the documents incorporated or deemed incorporated herein or therein by reference, any of which could cause actual results to differ materially from those indicated by our forward-looking statements.

The Private Securities Litigation Reform Act of 1995 and Section 27A of the Securities Act of 1933, as amended (the "Securities Act") do not protect any forward-looking statements that we make in connection with this offering. All forward-looking statements included in this prospectus and in the documents incorporated by reference in this prospectus are based on information available to us on the date of this prospectus or the date of the applicable document incorporated by reference. Except as required by law, we do not undertake any responsibility to update these forward-looking statements to address events or circumstances that occur after the date of this prospectus. Additionally, we do not undertake any responsibility to update you on the occurrence of any unanticipated events that may cause actual results to differ from those expressed or implied by these forward-looking statements.

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PROSPECTUS SUMMARY

This summary highlights certain information about us, this offering and information appearing elsewhere in this prospectus and in the documents we incorporate by reference. This summary is not complete and does not contain all of the information that you should consider before investing in our securities. To fully understand this offering and its consequences to you, you should read this entire prospectus carefully, including the information referred to under the heading "Risk Factors" on page 6 of this prospectus, and the financial statements and other information incorporated by reference in this prospectus, when making an investment decision. This is only a summary and may not contain all the information that is important to you. You should carefully read both this prospectus and any accompanying prospectus supplement, including the information incorporated by reference therein, and any other offering materials, together with the additional information described under the heading "Where You Can Find More Information."

About Us

The Company is a clinical stage biotechnology company focused on the clinical development and potential commercialization of its product candidate, leronlimab, which is being studied for its potential in solid-tumor oncology.

Our current business strategy is the clinical development of leronlimab, which may include the following:

Corporate Information

CytoDyn Inc. is a Delaware corporation with its principal executive offices at 1111 Main Street, Suite 660, Vancouver, Washington 98660, telephone (360) 980-8524. Our website can be found at www.cytodyn.com. We do not intend to incorporate any contents from our website into this prospectus. Effective August 27, 2015, we completed a reincorporation from Colorado to Delaware. Effective November 16, 2018, we implemented a holding company reorganization, and as a result we became the successor issuer and reporting company to the former CytoDyn Inc. (now our wholly owned subsidiary, CytoDyn Operations Inc.).

Smaller Reporting Company

We are a "smaller reporting company" as defined in the Securities Exchange Act of 1934, as amended (the "Exchange Act"). As a result, we may take advantage of certain reduced disclosure obligations available to smaller reporting companies, including the exemption from compliance with the auditor attestation requirements pursuant to the Sarbanes-Oxley Act of 2002, reduced disclosure about our executive compensation arrangements, and the requirements to provide only two years of audited financial statements in our annual reports and registration statements. We will continue to be a "smaller reporting company" as long as (1) we have a public float (i.e., the market value of our common stock held by non-affiliates) less than $250 million calculated as of the last business day of our most recently completed second fiscal quarter, or (2) our annual revenues are less than $100 million for our previous fiscal year and we have either no public float or a public float of less than $700 million as of the end of that fiscal year's second fiscal quarter. Reduced disclosures in our SEC filings due to our status as a "smaller reporting company" may make it harder for investors to analyze our results of operations and financial prospects.

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RISK FACTORS

Investing in our securities involves risks. You should carefully consider the risks, uncertainties and other factors described in our most recent Annual Report on Form 10-K, as may be supplemented and updated by subsequent Quarterly Reports on Form 10-Q and Current Reports on Form 8-K that we have filed or will file with the SEC, and in other documents that are incorporated by reference into this prospectus, as well as the risk factors and other information contained in or incorporated by reference into any accompanying prospectus supplement, before investing in any of our securities. Our financial condition, results of operations, and cash flows could be materially adversely affected by any of these risks. The risks and uncertainties described in the documents incorporated by reference herein are not the only risks and uncertainties that you may face.

For more information about our SEC filings, please see "Where You Can Find More Information" and "Incorporation of Certain Information by Reference."

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USE OF PROCEEDS

Unless we inform you otherwise in the applicable prospectus supplement, we will use the net proceeds from the sale of the securities offered by this prospectus and the exercise price from the exercise of any convertible securities, if any, for working capital and general corporate purposes.

When particular securities are offered, the prospectus supplement relating to that offering will set forth our intended use of the net proceeds received from the sale of those securities we sell. Pending the application of the net proceeds for these purposes, we expect to invest the proceeds in short-term, interest-bearing instruments or other investment-grade securities.

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THE SECURITIES WE MAY OFFER

The descriptions of the securities contained in this prospectus, together with the applicable prospectus supplements, summarize all of the material terms and provisions of the various types of securities that we may offer. We will describe in the applicable prospectus supplement relating to any securities the particular terms of the securities offered by that prospectus supplement. If we indicate in the applicable prospectus supplement, the terms of the securities may differ from the terms we have summarized below. We may also include in the prospectus supplement information about material United States federal income tax considerations relating to the securities, and the securities exchange, if any, on which the securities will be listed.

We may sell from time to time, in one or more offerings:

In this prospectus, we refer to the common stock, subscription rights, warrants and units collectively as "securities." The total dollar amount of all securities that we may sell pursuant to this prospectus will not exceed $100,000,000.

This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

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DESCRIPTION OF COMMON STOCK

The following description of our capital stock and provisions of our amended and restated certificate of incorporation and amended and restated bylaws are summaries. You should also refer to the amended and restated certificate of incorporation and the amended and restated bylaws, which are filed as exhibits to the registration statement of which this prospectus is part.

General

Our amended and restated certificate of incorporation authorizes us to issue up to 1,755,000,000 shares of capital stock, including 1,750,000,000 shares of common stock, par value $0.001 per share, and 5,000,000 shares of preferred stock, par value $0.001 per share. As of June 30, 2025, we had 1,251,533,754 shares of common stock outstanding, 19,000 shares of Series B Preferred Stock (as defined below), 6,335 shares of Series C Preferred Stock (as defined below) and 8,452 shares of Series D Preferred Stock (as defined below) issued and outstanding.

Common Stock

Each outstanding share of common stock entitles the holder to one vote, either in person or by proxy, on all matters submitted to a vote of stockholders, including the election of directors. There is no cumulative voting in the election of directors. All actions required or permitted to be taken by stockholders at an annual or special meeting of the stockholders must be effected at a duly called meeting, with a quorum present of a majority in voting power of the shares entitled to vote thereon. Special meetings of the stockholders may only be called by our Board acting pursuant to a resolution approved by the affirmative majority of the entire Board. Subject to the rights, if any, of any series of preferred stock to elect directors and to remove any director whom the holders of any such stock have the right to elect, any director (including persons elected by directors to fill vacancies in the Board) may be removed from office, with or without cause, only by the affirmative vote of the holders of at least a majority in voting power of the shares then entitled to vote at an election of directors. Other than with respect to actions permitted to be voted on by holders of preferred stock voting separately as a class or series, stockholders may not take action by written consent.

Subject to preferences which may be applicable to any outstanding shares of preferred stock from time to time, holders of our common stock have equal ratable rights to such dividends as may be declared from time to time by our Board out of funds legally available therefor. In the event of any liquidation, dissolution or winding-up of our affairs, holders of common stock will be entitled to share ratably in our remaining assets after provision for payment of amounts owed to creditors and preferences applicable to any outstanding shares of preferred stock. All outstanding shares of common stock are fully paid and nonassessable. Holders of common stock do not have preemptive rights.

Also, under Section 170 of the Delaware General Corporation Law (the "DGCL"), due to the Company's accumulated deficit of approximately $887.8 million as of May 31, 2025, the Company is prohibited from paying any dividends, whether in cash, other property, or shares of capital stock, until the deficiency in the amount of capital represented by the Company's issued and outstanding preferred stock shall have been repaired.

The rights, preferences and privileges of holders of common stock are subject to the rights of the holders of any outstanding shares of preferred stock. As more fully described in our Certificate of Incorporation, holders of our common stock are not entitled to vote on certain amendments to the Certificate of Incorporation related solely to our preferred stock.

Our common stock is presently quoted on the OTCQB tier of the OTC Markets marketplace under the trading symbol CYDY. Our transfer agent and registrar is Computershare Shareholder Services.

Anti-takeover Effects of Delaware Law and our Certificate of Incorporation, as amended

As described above, our Board is authorized to designate and issue shares of preferred stock in series and define all rights, preferences and privileges applicable to such series. This authority may be used to make it more difficult or less economically beneficial to acquire or seek to acquire us.

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Special meetings of the stockholders may only be called by our Board acting pursuant to a resolution approved by the affirmative majority of the entire Board. Stockholders may not take action by written consent.

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DESCRIPTION OF WARRANTS

We summarize below some of the provisions that will apply to the warrants unless the applicable prospectus supplement provides otherwise. This summary may not contain all information that is important to you. The complete terms of the warrants will be contained in the applicable warrant certificate and warrant agreement. These documents have been or will be included or incorporated by reference as exhibits to the registration statement of which this prospectus is a part. You should read the warrant certificate and the warrant agreement. You should also read the prospectus supplement, which will contain additional information and which may update or change some of the information below.

General

We may issue, together with common stock as units or separately, warrants for the purchase of shares of our common stock. The terms of each warrant will be discussed in the applicable prospectus supplement relating to the particular series of warrants. The form(s) of certificate representing the warrants and/or the warrant agreement, will be, in each case, filed with the SEC as an exhibit to a document incorporated by reference in the registration statement of which this prospectus is a part on or prior to the date of any prospectus supplement relating to an offering of the particular warrant. The following summary of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to a particular series of warrants.

The prospectus supplement relating to any series of warrants that are offered by this prospectus will describe, among other things, the following terms to the extent they are applicable to that series of warrants:

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Each warrant may entitle the holder to purchase for cash, or, in limited circumstances, by effecting a cashless exercise for, the number of shares of our common stock at the exercise price that is described in the applicable prospectus supplement. Warrants will be exercisable during the period of time described in the applicable prospectus supplement. After that period, unexercised warrants will be void. Warrants may be exercised in the manner described in the applicable prospectus supplement.

Unless the warrant agreement or prospectus supplement relating to any series of warrants expressly provides otherwise, in no event will we be required to "net cash" settle any warrant exercise.

A holder of a warrant will not have any of the rights of a holder of our common stock before the stock is purchased upon exercise of the warrant. Therefore, before a warrant is exercised, the holder of the warrant will not be entitled to receive any dividend payments or exercise any voting or other rights associated with shares of our common stock which may be purchased when the warrant is exercised.

Transfer Agent and Registrar

The transfer agent and registrar, if any, for any warrants will be set forth in the applicable prospectus supplement.

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DESCRIPTION OF SUBSCRIPTION RIGHTS

We summarize below some of the provisions that will apply to the subscription rights unless the applicable prospectus supplement provides otherwise. This summary may not contain all information that is important to you. The complete terms of such rights will be contained in the applicable rights certificate and rights agreement. These documents have been or will be included or incorporated by reference as exhibits to the registration statement of which this prospectus is a part. You should read the rights certificate and the rights agreement. You should also read the prospectus supplement, which will contain additional information and which may update or change some of the information below.

General

We may issue, together with common or warrants as units or separately, subscription rights for the purchase of shares of our common stock or warrants. The terms of each right will be discussed in the applicable prospectus supplement relating to the particular series of rights. The form(s) of certificate representing the rights and/or the rights agreement, will be, in each case, filed with the SEC as an exhibit to a document incorporated by reference in the registration statement of which this prospectus is a part on or prior to the date of any prospectus supplement relating to an offering of the particular rights. The following summary of material provisions of the rights and rights agreement is subject to, and qualified in its entirety by reference to, all the provisions of the rights agreement and rights certificate applicable to a particular series of rights.

Transfer Agent and Registrar

The transfer agent and registrar, if any, for any subscription rights will be set forth in the applicable prospectus supplement.

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DESCRIPTION OF UNITS

We may issue units comprised of one or more of the other securities described in this prospectus in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security (but, to the extent convertible securities are included in the units, the holder of the units will be deemed the holder of the convertible securities and not the holder of the underlying securities). The unit agreement under which a unit is issued, if any, may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date. The applicable prospectus supplement may describe:

This summary of certain general terms of units and any summary description of units in the applicable prospectus supplement do not purport to be complete and are qualified in their entirety by reference to all provisions of the applicable unit agreement and, if applicable, collateral arrangements and depositary arrangements relating to such units. The forms of the unit agreements and other documents relating to a particular issue of units will be filed with the SEC each time we issue units, and you should read those documents for provisions that may be important to you.

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PLAN OF DISTRIBUTION

Initial Offering and Sale of Securities

Unless otherwise set forth in a prospectus supplement accompanying this prospectus, we may sell the securities being offered hereby, from time to time, by one or more of the following methods:

Offerings of securities covered by this prospectus also may be made into an existing trading market for those securities in transactions at other than a fixed price, either:

Those at-the-market offerings, if any, will be conducted by underwriters acting as principal or agent of the Company, who may also be third-party sellers of securities as described above. The prospectus supplement with respect to the offered securities will set forth the terms of the offering of the offered securities, including:

The distribution of the securities may be effected from time to time in one or more transactions:

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Each prospectus supplement will set forth the manner and terms of an offering of securities including:

Sales Through Underwriters

If underwriters are used in the sale of some or all of the securities covered by this prospectus, the underwriters will acquire the securities for their own account. The underwriters may resell the securities, either directly to the public or to securities dealers, at various times in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to certain conditions. Unless indicated otherwise in a prospectus supplement, the underwriters will be obligated to purchase all the securities offered if any of the securities are purchased.

Any public offering price and any concessions allowed or reallowed to dealers may be changed intermittently.

Sales Through Agents

Unless otherwise indicated in the applicable prospectus supplement, when securities are sold through an agent, the designated agent will agree, for the period of its appointment as agent, to use specified efforts to sell the securities for our account and will receive commissions from us as will be set forth in the applicable prospectus supplement.

Securities bought in accordance with a redemption or repayment under their terms also may be offered and sold, if so indicated in the applicable prospectus supplement, in connection with a remarketing by one or more firms acting as principals for their own accounts or as agents for us. Any remarketing firm will be identified and the terms of its agreement, if any, with us and its compensation will be described in the prospectus supplement. Remarketing firms may be deemed to be underwriters in connection with the securities remarketed by them.

If so indicated in the applicable prospectus supplement, we may authorize agents, underwriters or dealers to solicit offers by certain specified institutions to purchase securities at a price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a future date specified in the prospectus supplement. These contracts will be subject only to those conditions set forth in the applicable prospectus supplement, and the prospectus supplement will set forth the commissions payable for solicitation of these contracts.

Direct Sales

We may also sell offered securities directly to institutional investors or others. In this case, no underwriters or agents would be involved. The terms of such sales will be described in the applicable prospectus supplement.

General Information

Broker-dealers, agents or underwriters may receive compensation in the form of discounts, concessions or commissions from us and/or the purchasers of securities for whom such broker-dealers, agents or underwriters may act as agents or to whom they sell as principal, or both. This compensation to a particular broker-dealer might be in excess of customary commissions.

Underwriters, dealers and agents that participate in any distribution of the offered securities may be deemed "underwriters" within the meaning of the Securities Act, so any discounts or commissions they receive in connection

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with the distribution may be deemed to be underwriting compensation. Those underwriters and agents may be entitled, under their agreements with us, to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution by us to payments that they may be required to make in respect of those civil liabilities. Certain of those underwriters or agents may be customers of, engage in transactions with, or perform services for, us or our affiliates in the ordinary course of business. We will identify any underwriters or agents, and describe their compensation, in a prospectus supplement. Any institutional investors or others that purchase offered securities directly, and then resell the securities, may be deemed to be underwriters, and any discounts or commissions received by them from us and any profit on the resale of the securities by them may be deemed to be underwriting discounts and commissions under the Securities Act.

We will file a supplement to this prospectus, if required, pursuant to Rule 424(b) under the Securities Act, if we enter into any material arrangement with a broker, dealer, agent or underwriter for the sale of securities through a block trade, special offering, exchange distribution or secondary distribution or a purchase by a broker or dealer. Such prospectus supplement will disclose:

In order to facilitate the offering of certain securities under this prospectus or an applicable prospectus supplement, certain persons participating in the offering of those securities may engage in transactions that stabilize, maintain or otherwise affect the price of those securities during and after the offering of those securities. Specifically, if the applicable prospectus supplement permits, the underwriters of those securities may over-allot or otherwise create a short position in those securities for their own account by selling more of those securities than have been sold to them by us and may elect to cover any such short position by purchasing those securities in the open market.

In addition, the underwriters may stabilize or maintain the price of those securities by bidding for or purchasing those securities in the open market and may impose penalty bids, under which selling concessions allowed to syndicate members or other broker-dealers participating in the offering are reclaimed if securities previously distributed in the offering are repurchased in connection with stabilization transactions or otherwise. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. The imposition of a penalty bid may also affect the price of securities to the extent that it discourages resales of the securities. No representation is made as to the magnitude or effect of any such stabilization or other transactions. Such transactions, if commenced, may be discontinued at any time.

In order to comply with the securities laws of certain states, if applicable, the securities must be sold in such jurisdictions only through registered or licensed brokers or dealers. In addition, in certain states the securities may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and is complied with.

Rule 15c6-1 under the Exchange Act generally requires that trades in the secondary market settle in one business day unless the parties to any such trade expressly agree otherwise. Your prospectus supplement may provide that the original issue date for your securities may be more than one scheduled business day after the trade date for your securities. Accordingly, in such a case, if you wish to trade securities on any date prior to the first business day before the original issue date for your securities, you will be required, by virtue of the fact that your securities initially are expected to settle

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in more than one scheduled business day after the trade date for your securities, to make alternative settlement arrangements to prevent a failed settlement.

This prospectus, any applicable prospectus supplement and any applicable pricing supplement in electronic format may be made available on the Internet sites of, or through other online services maintained by, us and/or one or more of the agents and/or dealers participating in an offering of securities, or by their affiliates. In those cases, prospective investors may be able to view offering terms online and, depending upon the particular agent or dealer, prospective investors may be allowed to place orders online.

Other than this prospectus, any applicable prospectus supplement and any applicable pricing supplement in electronic format, the information on our website or the website of any agent or dealer, and any information contained in any other website maintained by any agent or dealer:

There can be no assurance that we will sell all or any of the securities offered by this prospectus.

This prospectus may also be used in connection with any issuance of common stock upon exercise of a warrant if such issuance is not exempt from the registration requirements of the Securities Act.

In addition, we may issue the securities as a dividend or distribution or in a subscription rights offering to our existing securityholders. In some cases, we or dealers acting with us or on our behalf may also purchase securities and reoffer them to the public by one or more of the methods described above. This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement.

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LEGAL MATTERS

The validity of the securities offered hereby will be passed upon for us by Miller Nash LLP. If the validity of the securities offered hereby in connection with offerings made pursuant to this prospectus are passed upon by counsel for the underwriters, dealers or agents, if any, such counsel will be named in the prospectus supplement relating to such offering.

EXPERTS

The consolidated financial statements for the fiscal year ended May 31, 2025, incorporated in this prospectus by reference from our 2025 Form 10-K, have been audited by CBIZ CPAs P.C., an independent registered public accounting firm. Their report relating to the consolidated financial statements of CytoDyn Inc. contains one explanatory paragraph regarding substantial doubt as to CytoDyn Inc.'s ability to continue as a going concern. The report is incorporated herein by reference. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

The consolidated financial statements for the fiscal year ended May 31, 2024, incorporated in this prospectus by reference from our 2025 Form 10-K, have been audited by Marcum LLP, an independent registered public accounting firm. Their report relating to the consolidated financial statements of CytoDyn Inc. contains one explanatory paragraph regarding substantial doubt as to CytoDyn Inc.'s ability to continue as a going concern. The report is incorporated herein by reference. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

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WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of the Registration Statement. This prospectus does not contain all of the information in the Registration Statement, including the exhibits filed with or incorporated by reference into the Registration Statement. The Registration Statement, its exhibits, and the documents incorporated by reference into this prospectus and their exhibits, all contain information that is material to the offering of the securities hereby. Whenever a reference is made in this prospectus to any of our contracts or other documents, the reference may not be complete. You should refer to the exhibits that are a part of the Registration Statement in order to review a copy of the contract or documents. The Registration Statement and the exhibits are available through the SEC's EDGAR website.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the internet at the SEC's website at www.sec.gov and on our website at www.cytodyn.com. The information found on, or that can be accessed from or that is hyperlinked to, our website is not part of this prospectus or any applicable prospectus supplement.

We will provide you without charge, upon your oral or written request, with a copy of any or all reports, proxy statements and other documents we file with the SEC, as well as any or all of the documents incorporated by reference in this prospectus or the Registration Statement (other than exhibits to such documents unless such exhibits are specifically incorporated by reference into such documents). Requests for such copies should be directed to:

CytoDyn Inc.

1111 Main Street, Suite 660

Vancouver, Washington 98660

(360) 980-8524

You should rely only on the information in this prospectus and the additional information described above and under the heading "Incorporation of Certain Information by Reference" below. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information in this prospectus was accurate only on the date of the front cover of this prospectus. Our business, financial condition, results of operations and prospects may have changed since that date.

The representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference into this prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreement, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to "incorporate by reference" information that we file with it into this prospectus, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus. The information incorporated by reference is considered to be a part of this prospectus, and information that we file later with the SEC will automatically update and supersede information contained in this prospectus and any accompanying prospectus supplement.

We incorporate by reference the documents listed below that we have previously filed with the SEC:

All reports and other documents that we file with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this prospectus but before the termination of the offering of the securities hereunder will also be considered to be incorporated by reference into this prospectus from the date of the filing of these reports and documents, and will supersede the information herein; provided, however, that all reports, exhibits and other information that we "furnish" to the SEC will not be considered incorporated by reference into this prospectus. We undertake to provide without charge to each person (including any beneficial owner) who receives a copy of this prospectus, upon written or oral request, a copy of all of the preceding documents that are incorporated by reference (other than exhibits, unless the exhibits are specifically incorporated by reference into these documents). You may request a copy of these materials in the manner set forth under the heading "Where You Can Find More Information" above.

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$100,000,000

Common Stock

Warrants

Subscription Rights

Units

PROSPECTUS

September 29, 2025

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