Fund BBgBarc US Corporate High Yield Bond Index

Sector Weightings: Defines what % of each sector this fund holdscompared to its benchmark listed here.

QTD YTD

Portfolio Attribution: Describes how fund manager sector and stockweighting decisions affected returns.

Sector Attribution Details: Sector Fund Weight Q T D Y T D

Bkrg./Asst.Mgrs. 1.08 0.01 0.03

Basic Industry 10.28 0.07 -0.01

Capital Goods 11.30 -0.01 0.35

Communications 23.29 -0.16 0.23

Consumer Cyclical 7.69 -0.03 -0.08

Consumer Non-Cycl. 15.32 0.00 -0.26

Energy 7.84 -0.36 -0.14

Insurance 2.28 0.03 0.20

Other Industrial 1.59 -0.04 -0.08

Technology 7.11 -0.00 0.14

Transportation 4.12 0.05 -0.11

Other 8.10 -0.06 -0.27

Quarterly Portfolio Commentary:

Alpha Lyons, CFA Investment DirectorInvestment Experience: 7 Years

HIGHLIGHTS• High-yield fixed-income securities produced positive returns for thequarter and outperformed all other major fixed income asset categories.• The three major tiers (BB, B & CCC) were positive for the quarter andrelatively in line with each other, while CC & C were the only negativequality tiers in the high yield universe.• Banking, finance companies, and basic industry outperformed all otherindustries for the quarter.• An underweight to banking and consumer cyclical, combined with anoverweight to communications, weighed on relative returns.• Ratings exposures had very little impact on returns over the quarter.

Fund Objective: This Fund seeks to achieve a high level of total return, with an emphasis on current income, by investing primarily in high yield debtand related securities.

These materials and the platform of investments made available by MassMutual are offered without regard to the individualized needs of any plan, itsparticipants, or beneficiaries. These materials are not intended as impartial investment advice or to give advice in a fiduciary capacity to any plan.

NOT FDIC INSURED MAY LOSE VALUE NO BANK GUARANTEE

Quarterly Review

R5 SHARE CLASS TICKER: MPHSX

As of 12/31/2019

MassMutual Premier High Yield FundBarings LLC

Bkrg./Asst.M

grs.

Basic Industry

Capital G

oods

Com

munications

Consumer Cyclical

Consumer Non-Cycl.

Energy

Insurance

Other Industrial

Technology

Transportation

Other

0

6

12

18

24

Percent of P

ortfolio

Percent of P

ortfolio

Bkrg./Asst.M

grs.

Basic Industry

Capital G

oods

Com

munications

Consumer Cyclical

Consumer Non-Cycl.

Energy

Insurance

Other Industrial

Technology

Transportation

Other

-0.50

-0.25

0.00

0.25

0.50

Value Added vs. Benchmark (%

)Value Added vs. Benchmark (%

)

Quarterly Portfolio Commentary:

High-yield bonds continued their positive run and led fixed income asset category performance over the quarter and year. The asset category began thequarter with option-adjusted spreads at slightly over 400 basis points, despite a rise in spreads in early October, and rallied to end the quarter at spreadlevels of approximately 360 basis points. Within high-yield, the three major quality tiers (BB, B & CCC) performed relative in-line with each other, whileCC and C, only representing slightly more than 2% of the index, were the only negatively performing tiers. Sector wise, banking, finance companies andbasic industry were the best performing industries, while real estate investment trusts (REITs) and communications were the worst performing industries.

The Fund underperformed its benchmark and median peer for the quarter. Industry and rating allocations played a muted role in relative returns. Theprimary driver to relative underperformance was poor selection, particularly within the energy industry.An underweight to banking, the best performing industry in the quarter, combined with an overweight to communications, the second worst performingindustry, proved slight headwinds. Additionally, a slight exposure to CC weighed on returns. Most of the Fund’s underperformance came from poorselection in the energy industry. Within energy, Fieldwood Energy, Jupiter Resources, Farrellgas Parterns and Tullow Oil were the largest detractors.

Alternatively, an overweight to and strong selection within basic industry, combined with strong selection in transportation, insurance and financecompanies positively contributed to relative returns. Within transportation, tank truck transporter Kenan Advantage Group drove results. Within basicindustry, several names contributed to strong performance including First Quantum Minerals, Northwest Acquisitions and Suncoke Energy Partners.

The Fund maintains an overweight allocation to bonds rated CCC and a corresponding underweight allocation to BB-rated bonds, though these tilts havedecreased in recent years. However, Fund managers find the risk-return outlook for bonds in the lower-quality tiers more attractive with more potentialroom for spread compression. They therefore maintain an overweight to Fund holdings in the lower-quality tiers. Relative to the benchmark, the Fundended the quarter with its largest overweight positions in basic industry and transportation, and its largest underweights in the energy and consumercyclical sectors.

TICKER: MPHSX Fund Inception: 9/5/2000Morningstar Category: High Yield Bond

Average Annual Total Return

Q T D Y T D 1 Year 3 Year 5 Year 10 year

MassMutual Premier High Yield R5 2.01% 13.42% 13.42% 5.82% 6.25% 7.99%

BBgBarc US Corporate High Yield Bond Index 2.61% 14.32% 14.32% 6.37% 6.13% 7.57%

Category Average Return -- -- 12.62% 5.31% 4.87% 6.42%

Category Rank -- -- 48 36 7 4

# of Funds in Category -- -- 711 616 539 339

Performance shown is for class R5 shares. Gross expenses = 0.64%, Net expense = 0.64%. Max Sales charge for R5 is 0%.Performance shown is past performance. Past performance does not guarantee future results . You can lose money, includingloss of pr incipal , by invest ing in this fund. Investors should careful ly consider investment objectives, r isks , charges andexpenses. This and other important information is contained in the fund prospectuses and summary prospectuses, which can beobtained from www.massmutualfunds.com and should be read careful ly before invest ing. A l ist of the Fund’s holdings can alsobe obtained from www.massmutualfunds.com. Current performance may be lower or higher than return data quoted herein. Formore current information, including month-end performance, please cal l 1-866-444-2601. You cannot invest directly in an index. Issuesrated AAA, AA, A and BBB are considered investment grade and anything below BBB is considered non-investment grade.Investment Risks-The Fund’s Princ ipa l R isks include - Below Investment Grade Debt Securities Risk, Cash Position Risk, Convertible Securities Risk,Credit Risk, Defaulted and Distressed Securities Risk, Derivatives Risk, Fixed Income Securities Risk, Foreign Investment Risk; Emerging Markets Risk;Currency Risk, Frequent Trading/Portfolio Turnover Risk, Inflation Risk, Leveraging Risk, Liquidity Risk, Management Risk, Market Risk, Mortgage andAsset-Backed Secuirites Risk, Preffered Stock Risk, Repurchase Agreement Risk, Reverse Repurchase Agreement Transaction Risk, U.S. GovernmentSecurities Risk, Valuation Risk. Please refer to the summary prospectus (a copy can be obtained by sending an email to fundinfo@massmutual.com) formore information on the specific risks.The Morningstar percenti le ranking is based on the fund’s total-return percenti le rank relat ive to al l funds that have the samecategory for the same t ime period. The highest (or most favorable) percentile rank is 1%, and the lowest (or least favorable) percentile rank is 100%.Morningstar total return includes both income and capital gains or losses and is not adjusted for sales charges. © 2019 Morningstar, Inc. All RightsReserved. The information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) isnot warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from anyuse of this information.

MassMutual Premier High Yield Fund

RS9093b 418 RS-45395-06

© 2020 Massachusetts Mutual Life Insurance Company (MassMutual®), Springfield, MA. All rights reserved. www.MassMutual.com Principal Underwriter:MML Distributors, LLC. (MMLD) Member FINRA and SIPC (www.FINRA.org and www.SIPC.org) MMLD is a subsidiary of Massachusetts Mutual LifeInsurance Company, 100 Bright Meadow Blvd., Enfield, CT 06082. Investment advisory services provided to the Funds by MML Investment Advisers, LLC.

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