# EDGAR Filing Document

**Accession Number:** 0000916053
**File Stem:** 0001104659-23-008748
**Filing Date:** 2023-1
**Character Count:** 37767
**Document Hash:** 17dddaf165095eda9fde0a8d4a903387
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-23-008748.hdr.sgml**: 20230131

**ACCESSION NUMBER**: 0001104659-23-008748

**CONFORMED SUBMISSION TYPE**: 497K

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20230131

**DATE AS OF CHANGE**: 20230131

**EFFECTIVENESS DATE**: 20230131

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MASSMUTUAL SELECT FUNDS
- **CENTRAL INDEX KEY:** 0000916053
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** MA
- **FISCAL YEAR END:** 0930

**FILING VALUES:**
- **FORM TYPE:** 497K
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-73824
- **FILM NUMBER:** 23573586

**BUSINESS ADDRESS:**
- **STREET 1:** 1295 STATE STREET
- **CITY:** SPRINGFIELD
- **STATE:** MA
- **ZIP:** 01111
- **BUSINESS PHONE:** 413-744-1000

**MAIL ADDRESS:**
- **STREET 1:** 1295 STATE STREET
- **CITY:** SPRINGFIELD
- **STATE:** MA
- **ZIP:** 01111

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** MASSMUTUAL INSTITUTIONAL FUNDS
- **DATE OF NAME CHANGE:** 19931213

## Series and Classes Contracts Data

### MassMutual Strategic Bond Fund (Series ID: S000003673)

| Class ID   | Class Name           | Ticker Symbol   |
|:---|:---|:---|
| C000010252 | Class A              | MSBAX           |
| C000010253 | Administrative Class | MSBLX           |
| C000010254 | Class R3             | MSBNX           |
| C000010255 | Class R5             | MBSSX           |
| C000010256 | Service Class        | MBSYX           |
| C000140369 | Class I              | MSBZX           |
| C000140370 | Class R4             | MSBRX           |
| C000240795 | Class Y              |  |

![[MISSING IMAGE: lg_massmutualdots-k.jpg]](lg_massmutualdots-k.jpg)

Summary Prospectus February 1, 2023

## MassMutual Funds

#### MassMutual Strategic Bond Fund
**Ticker:** Class I–MSBZX, Class R5–MBSSX, Service Class–MBSYX, Administrative Class–MSBLX, Class R4–MSBRX, Class A–MSBAX, Class R3–MSBNX, Class Y–MMNMX

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 fundinfo@massmutual.com.

#### INVESTMENT OBJECTIVE
This Fund seeks a superior total rate of return by investing in fixed income instruments.

#### 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 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 142 of the Fund's Prospectus or from your financial professional.

#### Shareholder Fees (fees paid directly from your investment)

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| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | **Class I**  | **Class R5**  | **Service <br>Class**  | **Administrative <br>Class**  | **Class R4**  | **Class A**  | **Class R3**  | **Class Y**  |
|  Maximum Sales Charge (Load) Imposed on Purchases (as a % of offering price)  |  |  |  |  |  | 4.25%  |  |  |
|  Maximum Deferred Sales Charge (Load) (as a % of the lower of the original offering price or redemption proceeds)  |  |  |  |  |  |  |  |  |

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

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | **Class I**  | **Class R5**  | **Service <br>Class**  | **Administrative <br>Class**  | **Class R4**  | **Class A**  | **Class R3**  | **Class Y**  |
| Management Fees | 0.39% | 0.39% | 0.39% | 0.39% | 0.39% | 0.39% | 0.39% | 0.39%  |
|  Distribution and Service (Rule 12b-1) Fees  |  |  |  |  | 0.25%  | 0.25%  | 0.50%  |  |
| Other Expenses | 0.12% | 0.22% | 0.32% | 0.42% | 0.32% | 0.42% | 0.32% | 0.22%<sup>(1)</sup>  |
|  **Total Annual Fund Operating Expenses**  | **0.51%**  | **0.61%**  | **0.71%**  | **0.81%**  | **0.96%**  | **1.06%**  | **1.21%**  | **0.61%**  |
| Fee Waiver | (0.05%)  | (0.05%)  | (0.05%)  | (0.05%)  | (0.05%)  | (0.05%)  | (0.05%)  | (0.05%)  |
|  Total Annual Fund Operating Expenses after Fee Waiver<sup>(2)</sup>  | 0.46% | 0.56% | 0.66% | 0.76% | 0.91% | 1.01% | 1.16% | 0.56%  |

---

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

(1) Other Expenses are based on estimated amounts for the current fiscal year of the Fund.

(2) The expenses in the above table reflect a written agreement by MML Advisers to waive 0.05% of its management fees through January 31, 2024. This agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

#### 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 initial 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:

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| | | | | |
|:---|:---|:---|:---|:---|
| | **1 Year**  | **3 Years**  | **5 Years**  | **10 Years**  |
| Class I | $47 | $159 | $280 | $636 |
| Class R5 | $57 | $190 | $335 | $757 |
| Service Class | $67 | $222 | $390 | $878 |
| Administrative Class  | $78 | $254 | $445 | $997 |
| Class R4 | $93 | $301 | $526 | $1173 |
| Class A | $524 | $743 | $980 | $1660 |
| Class R3 | $118 | $379 | $660 | $1462 |
| Class Y | $57 | $190 | $335 | $757 |

---

#### 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 118% of the average value of its portfolio.

#### INVESTMENTS, RISKS, AND PERFORMANCE

#### Principal Investment Strategies
Under normal circumstances, the Fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in U.S. dollar-denominated fixed income securities and other debt instruments of domestic and foreign entities, including corporate bonds, securities issued or guaranteed as to principal or interest by the U.S. Government or its agencies or instrumentalities, mortgage-backed securities, and money market instruments. The Fund may invest up to 20% of its total assets in non-U.S.

dollar-denominated securities of these entities. The Fund may invest in emerging markets. The Fund may but will not necessarily engage in foreign currency transactions, including forward contracts, options on currency, futures contracts, and swap contracts, to attempt to seek to hedge or to protect against adverse changes in currency exchange rates. In pursuing its investment objective, the Fund may (but is not obligated to) use a wide variety of additional exchange-traded and over-the-counter derivatives, including futures contracts (for hedging purposes or to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund's portfolio); interest rate swaps (for hedging purposes or to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund's portfolio); credit default swaps (for hedging purposes, to earn additional income, or as a substitute for direct investments); and hybrid instruments (as a substitute for direct investments). The Fund may also purchase and sell exchange-traded and over-the-counter options for hedging purposes, to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund's portfolio, or as a substitute for direct investments. Use of derivatives by the Fund may create investment leverage. The Fund may purchase and sell securities on a when-issued, delayed delivery, or forward commitment basis. The Fund may also invest in money market securities, including commercial paper. 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 managed by three subadvisers, *Western Asset Management Company, LLC* ("Western Asset"), *Western Asset Management Company Limited* ("Western Asset Limited"), and *Brandywine Global Investment Management, LLC* ("Brandywine Global"), each being responsible for a portion of the portfolio, although they may manage different amounts of the Fund's assets.

The Fund invests primarily in investment grade securities (rated Baa or higher by Moody's or BBB or higher by Standard & Poor's, or, if unrated, determined by the subadviser to be of comparable quality), but may invest up to 25% of the portfolio in below investment grade debt securities ("junk" or "high yield" bonds), including securities in default. In the event that a security is downgraded

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after its purchase by the Fund, the Fund may continue to hold the security if Western Asset or Brandywine Global consider that doing so would be consistent with the Fund's investment objective. Certain fixed income securities in which the Fund may invest pay interest at variable or floating rates. Variable rate securities tend to reset at specified intervals, while floating rate securities may reset upon a change in a specified index rate. In most cases, these reset provisions reduce the impact of changes in market interest rates on the value of the security. However, some securities do not track the underlying index directly, but reset based on formulas that may produce a leveraging effect; others may also provide for interest payments that vary inversely with market rates. The market prices of these securities may fluctuate significantly when interest rates change. The Fund may also acquire, and subsequently hold, warrants and other equity interests. The Fund's effective duration is normally expected to be between three and nine years. If the Fund's effective duration falls outside of this range, the Fund will take action to bring it within its expected range within a reasonable period of time. Duration measures the price sensitivity of a bond to changes in interest rates. Duration is the dollar weighted average time to maturity of a bond utilizing the present value of all future cash flows. Effective duration measures the price sensitivity of a bond with embedded options to changes in interest rates. It provides a more accurate measure of price volatility when, due to the embedded options, the cash flow characteristics of the bond change as interest rates shift.

Western Asset invests in the fixed income markets seeking to exceed returns of the Fund's benchmark while approximating benchmark risk. Western Asset focuses on sector allocation, issue selection, duration weighting, and term structure when buying and selling securities for the Fund. Western Asset emphasizes diversification, the use of multiple strategies and identification of long-term trends. The three key factors that determine Western Asset's allocation decisions for the Fund are: Western Asset's broad economic outlook, its review of historical yield spreads for debt instruments versus Treasuries, and its evaluation of changes in credit quality and the corresponding impact on prices. Western Asset will determine the portion of the Fund's assets it is responsible for to be allocated to non-U.S. dollar denominated securities from time to time. Western Asset Limited, an affiliate of Western Asset, has subadvisory responsibility for Western Asset's non-U.S. dollar

denominated investments. Western Asset Limited will select such investments based on its consideration of factors such as relative interest rates, inflation rates, exchange rates, monetary and fiscal policies, and trade and current account balances.

Brandywine Global follows a value-driven, active, strategic approach to buying and selling securities for the Fund that considers duration, yield curve exposure, credit exposure, and sector weightings that are based upon the broad investment themes of its global macroeconomic research platform as they apply to U.S. markets. As part of its investment process, Brandywine Global develops an outlook for macroeconomic variables such as inflation, growth, and unemployment in the U.S., as well as in other countries that may impact U.S. fixed income sectors. Brandywine Global then develops a viewpoint on the business cycle and positions the strategy's duration, sector weighting and credit exposures accordingly.

The Fund expects that it will engage in active and frequent trading and so will typically have a relatively high portfolio turnover rate.

#### 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.

***Fixed Income Securities Risk*** The values of fixed income securities typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income

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securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund's fixed income investment typically will decline), and credit risk.

***Below Investment Grade Debt Securities Risk*** Below investment grade debt securities, commonly known as "junk" or "high yield" bonds, have speculative characteristics and involve greater volatility of price and yield, greater risk of loss of principal and interest, and generally reflect a greater possibility of an adverse change in financial condition that could affect an issuer's ability to honor its obligations.

***Credit Risk*** Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty's ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

***Derivatives Risk*** Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives' original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

***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. 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.

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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 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.

***Mortgage- and Asset-Backed Securities Risk*** Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government

agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. Investments that receive only the interest portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund's mortgage-backed investments.

***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.

***Defaulted and Distressed Securities Risk*** Because the issuer of such securities is in default and is likely to be in distressed financial condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is uncertain. To the extent the Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

***Frequent Trading/Portfolio Turnover Risk*** Portfolio turnover generally involves some expense to the Fund and may result in the realization of taxable capital gains (including short-term gains). The trading costs and tax effects associated with portfolio turnover may adversely affect the Fund's performance.

***Hedging Risk*** The Fund's attempts at hedging and taking long and short positions in currencies may not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

***Inflation Risk*** The value of assets or income from the Fund's investments will be less in the future

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as inflation decreases the value of money. As inflation increases, the value of the Fund's assets can decline as can the value of the Fund's distributions. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund's investments may not keep pace with inflation, which may result in losses to the Fund's investors.

***Leveraging Risk*** Instruments and transactions, including derivatives transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

***LIBOR Risk*** Certain instruments in which the Fund may invest rely in some fashion upon the London-Interbank Offered Rate ("LIBOR"). On July 27, 2017, the head of the United Kingdom's Financial Conduct Authority announced a desire to phase out the use of LIBOR by the end of 2021. The administrator of LIBOR ceased publication of most LIBOR settings on a representative basis at the end of 2021 and is expected to cease publication of remaining U.S. dollar LIBOR settings on a representative basis after June 30, 2023. In addition, global regulators have announced that, with limited exceptions, no new LIBOR-based contracts should be entered into after 2021. Actions by regulators have resulted in the establishment of alternative reference rates to LIBOR in most major currencies. Market participants are focused on the transition mechanisms by which the reference rate in existing contracts or instruments may be amended, whether through market wide protocols, fallback contractual provisions, bespoke negotiations or amendments, or otherwise. Markets are developing in response to these new rates, and questions around liquidity in these rates and how to appropriately adjust these rates to eliminate any economic value transfer at the time of transition remain a significant concern for the Fund. Neither the effect of the transition process nor its ultimate success can yet be known. The transition process may involve, among other things, increased volatility or illiquidity in markets for instruments that rely on LIBOR. In addition, uncertainty and volatility arising from the transition may result in a reduction in the value of certain LIBOR-based instruments held by the Fund or reduce the effectiveness of related transactions such as hedges. Any such effects of the transition away from

LIBOR, as well as other unforeseen effects, could result in losses to the Fund.

***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 Risk*** The Fund relies on the manager's investment analysis and its selection of investments to achieve its investment objective. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses.

***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.

***Reinvestment Risk*** Income from the Fund's portfolio will decline if and when the Fund invests the proceeds from matured, traded, or called debt obligations at market interest rates that are below the portfolio's current earnings rate. A decline in income could affect the Fund's overall return.

***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.

***Sovereign Debt Obligations Risk*** Investments in debt securities issued by governments or by

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government agencies and instrumentalities involve the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. Many sovereign debt obligations may be rated below investment grade ("junk" or "high yield" bonds). Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt.

***U.S. Government Securities Risk*** Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

***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.

***When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk*** These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

#### 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. Performance for Class I and Class R4 shares of the Fund for periods prior to their inception date (04/01/14) and 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, adjusted for Class R4 shares to reflect Class R4 expenses. 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/funds or by calling 1-888-309-3539.

#### Annual Performance

#### Class R5 Shares
![[MISSING IMAGE: mvntlt7tbtjah58dfccb4b2g29v3.jpg]](mvntlt7tbtjah58dfccb4b2g29v3.jpg)

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
| Highest Quarter:  | 2Q '20,  | 7.24%  | Lowest Quarter: | 1Q '22,  | –6.43% |

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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, 2022)

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| | | | | |
|:---|:---|:---|:---|:---|
|  |  | **One <br>Year**  | **Five <br>Years**  | **Ten <br>Years**  |
| Class R5  | Return Before <br> Taxes  | -15.48% | -0.06% | 1.58% |
| Class R5  | Return After Taxes on Distributions | -16.00% | -1.49% | 0.20% |
| Class R5  | Return After Taxes on Distributions and Sales of Fund Shares | -9.15% | -0.48% | 0.68% |
| Class I | Return Before <br> Taxes | -15.51% | 0.02% | 1.65% |
| Service Class  | Return Before <br> Taxes | -15.66% | -0.17% | 1.47% |
| Administrative <br> Class | Return Before <br> Taxes | -15.69% | -0.26% | 1.37% |
| Class R4 | Return Before <br> Taxes | -15.84% | -0.39% | 1.22% |
| Class A | Return Before <br> Taxes | -19.51% | -1.39% | 0.67% |
| Class R3 | Return Before <br> Taxes | -16.15% | -0.68% | 0.94% |
| Class Y | Return Before <br> Taxes | -15.48% | -0.06% | 1.58% |
| Bloomberg U.S. Aggregate <br> Bond Index (reflects no <br> deduction for fees, expenses, or <br> taxes) | Bloomberg U.S. Aggregate <br> Bond Index (reflects no <br> deduction for fees, expenses, or <br> taxes) | -13.01% | 0.02% | 1.06% |

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#### MANAGEMENT
**Investment Adviser:** MML Investment Advisers, LLC ("MML Advisers")

**Subadviser(s):** Western Asset Management Company, LLC ("Western Asset")

Western Asset Management Company Limited ("Western Asset Limited")

Brandywine Global Investment Management, LLC ("Brandywine Global")

#### Portfolio Manager(s):
**John L. Bellows, CFA, PhD** is a Portfolio Manager at Western Asset and Western Asset Limited. He has managed the Fund since February 2020.

&nbsp;&nbsp;&nbsp;&nbsp; **S. Kenneth Leech** is the Chief Investment Officer and a Portfolio Manager at Western Asset and Western Asset Limited. He has managed the Fund since March 2014.

**Mark S. Lindbloom** is a Portfolio Manager at Western Asset and Western Asset Limited. He has managed the Fund since December 2005.

**Frederick R. Marki, CFA** is a Portfolio Manager at Western Asset and Western Asset Limited. He has managed the Fund since February 2020.

**Julien A. Scholnick, CFA** is a Portfolio Manager at Western Asset and Western Asset Limited. He has managed the Fund since February 2020.

**Tracy Chen, CFA, CAIA** is a Portfolio Manager at Brandywine Global. She has managed the Fund since August 2021.

**Brian Kloss, JD, CPA** is a Portfolio Manager at Brandywine Global. He has managed the Fund since August 2021.

**Jack McIntyre, CFA** is a Portfolio Manager at Brandywine Global. He has managed the Fund since August 2021.

**Anujeet Sareen, CFA** is a Portfolio Manager at Brandywine Global. He has managed the Fund since August 2021.

#### PURCHASE AND SALE OF FUND SHARES
Shares of the Fund are generally available through distribution channels, such as broker-dealers or financial institutions, and to retirement plans, 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).

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| | |
|:---|:---|
| **Purchase Minimums\*** | **Purchase Minimums\*** |
| | **Class Y**  |
| **Initial Investment** | **$100000**  |
| **Subsequent Investment** | **$250**  |

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The Fund reserves the right to change or waive the investment minimums. For retirement plans, the investment minimum is $250 for each of the initial investment and subsequent investments.

#### 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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