Summary Prospectus by Investment Company (Form 497K)

MassMutual Funds

MassMutual Blue Chip Growth Fund

Ticker: Class I-MBCZX, Class R5-MBCSX, Service Class-MBCYX, Administrative Class-MBCLX,
Class R4-MBGFX, Class A-MBCGX, Class R3-MBCNX, Class Y-MMZMX

Before you invest, you may want to review the Fund's prospectus, which contains more information about the Fund and its risks. You can find the Fund's prospectus and other information about the Fund online at https://www.massmutual.com/funds. You can also get this information at no cost by calling 1-888-309-3539 or by sending an email request to [email protected].

INVESTMENT OBJECTIVE

This Fund seeks growth of capital over the long-term.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay brokerage commissions and other fees to financial intermediaries which are not reflected in the tables and examples below. For Class A shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in MassMutual Funds. More information about these and other discounts is available in the section titled Sales Charges by Class beginning on page 55 of the Fund's Prospectus or from your financial professional.

Shareholder Fees (fees paid directly from your investment)

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

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Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. For Class A shares, the example includes the front-end sales charge. The example also assumes that your investment earns a 5% return each year and that the Fund's operating expenses are exactly as described in the preceding table. Although your actual costs  may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 14% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of net assets (plus the amount of any borrowings for investment purposes) in the common stocks of large- and medium-sized blue chip growth companies. The Fund is managed by two subadvisers, each being responsible for a portion of the portfolio, although they may manage different amounts of the Fund's assets. The Fund's subadvisers, T. Rowe Price Associates, Inc. ("T. Rowe Price") and Loomis, Sayles & Company, L.P. ("Loomis Sayles"), currently define blue chip growth companies to mean firms that, in their view, are well-established in their industries and have the potential for above-average earnings growth. Equity securities may include common stocks, preferred

stocks, securities convertible into common or preferred stock, rights, and warrants. While most assets will be invested in equity securities of U.S. companies, the Fund may also invest up to 20% of its total assets in foreign securities and American Depositary Receipts ("ADRs"), including emerging market securities. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. The Fund is non-diversified, which means that it may hold larger positions in a smaller number of issuers than a diversified fund.

In selecting securities, T. Rowe Price generally seeks to identify companies with a leading market position, seasoned management, and strong financial fundamentals. T. Rowe Price believes that solid company fundamentals (with emphasis on the potential for above-average growth) combined with a positive industry outlook will result in a higher stock price. It is anticipated that some of the companies targeted will have good prospects for dividend growth and T. Rowe Price may at times invest significantly in stocks of information technology companies. T. Rowe Price may sell assets for a variety of reasons, including in response to a change in the original investment considerations or to limit losses, adjust the characteristics of the overall portfolio, or redeploy assets into different opportunities.

In pursuing the Fund's investment objective, T. Rowe Price has the discretion to purchase some securities that do not meet its normal investment criteria described above, when it believes there is an opportunity for substantial appreciation (such as, for example, T. Rowe Price believes a security could increase in value as a result of a change in management, an extraordinary corporate event, a new product introduction or innovation, or a favorable competitive development).

In selecting securities, Loomis Sayles emphasizes companies with sustainable competitive advantages versus others, long-term structural growth drivers that will lead to above-average future cash flow growth, attractive cash flow returns on invested capital, and management teams focused on creating long-term value for shareholders. Loomis Sayles aims to invest in companies when they trade at a significant discount to Loomis Sayles' estimate of intrinsic value (i.e., companies with share prices trading significantly below what Loomis Sayles believes the share price should be). Loomis Sayles will consider selling a portfolio investment when (i) it believes an unfavorable structural change occurs within a given business or the markets in which it

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operates, (ii) a critical underlying investment assumption is flawed, (iii) a more attractive reward-to-risk opportunity becomes available, (iv) the current price fully reflects intrinsic value, or (v) for other investment reasons which it deems appropriate.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, and other trade disputes may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment

in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund's investment adviser or  subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund's assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility

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and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on future earnings or cash flow expectations, and can be more volatile than the market in general.

Large Company Risk Large-capitalization stocks as a group could fall out of favor with the market, causing the Fund's investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager's investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager's assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser's, subadviser's, or another service provider's internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund's portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Non-Diversification Risk Because the Fund may invest a larger percentage of its assets in a single issuer or in a smaller number of issuers as compared to a diversified fund, the Fund's performance could be closely tied to the value of one issuer or a small number of issuers and could be more volatile than the performance of a diversified fund.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to

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additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund's portfolio, and the Fund's performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund's performance from year to year for Class R5 shares. The table shows how the Fund's average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and an additional index that MML Advisers believes more closely reflects the market segments in which the Fund invests (Russell 1000^® Growth Index). Performance for Class Y shares of the Fund for periods prior to its inception date (02/01/23) is based on the performance of Class R5 shares. Performance for Class A shares of the Fund reflects any applicable sales charge. Past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. More up-to-date performance information is available at https://www.massmutual.com/product-performance/mutual-funds or by calling 1-888-309-3539.

Annual Performance

Class R5 Shares

After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class R5  only. After-tax returns for other classes will vary.

Average Annual Total Returns
(for the periods ended December 31, 2025)

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC ("MML Advisers")

Subadviser(s): T. Rowe Price Associates, Inc. ("T. Rowe Price")

Loomis, Sayles & Company, L.P. ("Loomis Sayles")

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Portfolio Manager(s):

Paul D. Greene II is a Portfolio Manager at T. Rowe Price. He has managed the Fund since October 2021.

Aziz V. Hamzaogullari, CFA is the Chief Investment Officer and Founder of the Growth Equity Strategies Team and a member of the Board of Directors at Loomis Sayles. He has managed the Fund since January 2015.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available through various financial intermediaries, such as retirement plan recordkeepers, broker-dealers, financial institutions, and insurance companies, and to other institutional investors and individual retirement accounts. Fund shares are redeemable on any business day by written request, telephone, or internet (available to certain customers).

TAX INFORMATION

The Fund intends to make distributions that may be taxed as ordinary income, qualified dividend income, or capital gains, unless you are an investor eligible for preferential tax treatment.

PAYMENTS TO BROKER-DEALERS AND OTHER FINANCIAL INTERMEDIARIES

If you purchase the Fund through a broker-dealer or other financial intermediary, the intermediary may receive a one-time or continuing payments from the Fund, MML Advisers or its affiliates, or others for the sale of Fund shares or continuing shareholder services provided by the intermediary. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary to recommend the Fund over another investment. You should contact your intermediary to obtain more information about the compensation it may receive in connection with your investment.

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