Fund S&P 500® Index

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

QTD YTD

Sector Attribution: Describes how sector weighting decisions affectedreturns by sector.

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

Communication Services 5.43 -0.31 0.22

Consumer Discretionary 13.92 0.02 0.53

Consumer Staples 6.80 -0.07 -0.43

Energy 4.71 0.27 0.42

Financials 18.46 0.06 0.26

Health Care 15.24 -0.48 0.01

Industrials 9.22 0.19 0.86

Information Technology 18.78 -0.15 0.48

Materials 0.63 0.05 0.17

Real Estate 3.18 -0.02 0.44

Utilities 1.44 -0.14 -0.25

Cash 2.19 -0.02 -0.26

Quarterly Portfolio Commentary:

Phil Connor, CFA Investment DirectorInvestment Experience: 29 Years

HIGHLIGHTS • U.S. large-cap stocks posted modest gains in the third quarter of 2019,adding to strong year-to-date performance.• Most sectors of the S&P 500® Index provided positive return in thequarter.• Defensive sectors of the Index, such as utilities and consumer staples,provided the strongest returns - although healthcare detracted.• Fund performance lagged the Index due to both stock selection andsector allocation.• Stock selection was weakest in healthcare and communication services,while sector allocation detracted primarily from an underweight toutilities.

Fund Objective: The Fund seeks a high total return.

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: MMSSX

As of 09/30/2019

MassMutual Premier Main Street FundInvesco Advisers, Inc.

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Quarterly Portfolio Commentary

The S&P 500 Index ended the third quarter of the year with a modest return of 1.70%. While the U.S. trade war with China continued to weigh on themarket, two interest rate cuts by the Federal Reserve provided some optimism. Eight of eleven equity sectors generated positive returns, led by the moredefensive utilities and consumer staples sectors. The real estate sector also posted strong returns; though its smaller weight in the index limited its effecton returns. Domestic large-cap stocks outperformed mid- and small-cap stocks in the quarter. From a style perspective, growth stocks modestly outpacedvalue stocks across the large-cap spectrum.

Fund performance lagged the benchmark in the quarter, however continues to have excess return on a year-to-date basis. Stock selection results inhealthcare detracted the most from performance. Results for the sector were weak in both the services & equipment, as well as pharmaceuticals &biotechnology segments. UnitedHealth Group, one of the Fund’s top holdings, was a large detractor as the stock price fell over 10% on investor concernabout near-term prospects for healthcare reform - particularly surrounding proposals that would limit the role of private healthcare firms. Fund exposureto Elanco Animal Health Inc. was another driver of weak performance in healthcare. Elanco is one of the largest companies in the animal-health businessand its stock fell significantly during the quarter following the announcement that it would acquire the animal health business of BayerAG. While the dealpresents additional growth opportunity, investors reacted negatively to the acquisition as it raises the company’s debt level and comes with operating risk.

The communication services sector was another area of notable detraction for the Funds performance during the quarter. The underperformance wasprimarily driven by weakness in Facebook Inc. stock; also a top ten holding of the Fund. The stock fell as management advised of lower earnings. StockSelection in the consumer staples sector modestly detracted with tobacco giant Philip Morris’s stock pullinged back from a recent run up as Fundmanagement was exiting the position. Also detracting was the Fund’s underweight to the utilities sector. The sector is a small part of the benchmark, andlikewise to the Fund, however during the quarter it had the strongest overall absolute return among sectors of the benchmark.

On the positive side, stock selection was broadly favorable across other sectors. Holdings in the energy sector stand out for their positive impact. TheFund’s strong active weight in integrated energy company Suncor Energy Inc. was particularly beneficial as the stock price held up nicely against thesector’s decline. The Fund experienced additional benefits driven by selections in industrials, consumer discretionary, and financials. The Fund continuesto emphasize stocks of companies that, in the Fund manager’s view, have sustainable earnings advantages.

TICKER: MMSSX Fund Inception: 12/31/2004Morningstar Category: Large Cap Blend

Average Annual Total Return

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

MassMutual Premier Main Street R5 0.82% 22.21% 5.47% 11.14% 9.31% 12.18%

S&P 500® Index 1.70% 20.55% 4.25% 13.39% 10.84% 13.24%

Category Average Return -- -- 3.00% 11.70% 8.98% 11.76%

Category Rank -- -- 22 66 51 49

# of Funds in Category -- -- 1,423 1,222 1,086 825

Performance shown is for class R5 shares. Gross expenses = 0.81%, Net expense = 0.81%. 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.Investment Risks - The Fund’s Princ ipa l R isks include - Cash Position Risk, Equity Securities Risk, Foreign Investment; Emerging Markets; Currency Risk,Growth Company Risk, Large Company Risk, Liquidity Risk, Management Risk, Market Risk, Small and Mid-Cap Company Risk, Valuation Risk, ValueCompany Risk. Please refer to the summary prospectus (a copy can be obtained by sending an email to fundinfo@massmutual.com) for more informationon 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 Main Street Fund

Quarter to Date:

Top 5 Contributors F u n dW e i g h t

AbsoluteReturn*

Portfol ioContr ibut ion

Procter & Gamble Co 3.11 14.17 0.41

Microsoft Corp 7.34 4.14 0.30

The Home Depot Inc 2.34 12.24 0.27

JPMorgan Chase & Co 4.54 6.01 0.27

Lockheed Martin Corp 3.01 7.91 0.24

Top 5 Detractors F u n dW e i g h t

AbsoluteReturn*

Portfol ioContr ibut ion

Elanco Animal Health Inc 1.89 -21.33 -0.46

UnitedHealth Group Inc 3.39 -10.53 -0.43

Amazon.com Inc 3.72 -8.33 -0.32

Facebook Inc A 3.52 -7.73 -0.29

Ulta Beauty Inc 0.68 -27.74 -0.22

Year to Date:

Top 5 Contributors F u n dW e i g h t

AbsoluteReturn*

Portfol ioContr ibut ion

Microsoft Corp 6.90 38.44 2.54

Motorola Solutions Inc 3.08 49.78 1.42

Lockheed Martin Corp 2.81 51.87 1.34

Facebook Inc A 3.80 35.85 1.27

Prologis Inc 2.96 48.10 1.26

Top 5 Detractors F u n dW e i g h t

AbsoluteReturn*

Portfol ioContr ibut ion

UnitedHealth Group Inc 3.16 -11.64 -0.63

Elanco Animal Health Inc 1.61 -12.82 -0.30

The Kraft Heinz Co 0.23 -22.89 -0.26

NetApp Inc 0.71 -20.35 -0.21

SVB Financial Group 0.71 -14.24 -0.20

RS9093b RS-45365-05

Portfolio Holdings:

Fund Weightings are shown as an average for the time period.*Absolute Return is the return that an asset achieves over a certain period of time. This measure looks at the appreciation or depreciation (expressed as apercentage) that a holding achieves over a given period of time.For a complete listing of fund holdings, visit massmutualfunds.com or please call 1-866-444-2601. The mention of individual stocks and other securities inthis document does not constitute investment advice.

MassMutual Premier Main Street Fund

© 2019 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 Life Insurance Company, 100 Bright Meadow Blvd., Enfield, CT 06082. Investment advisory services provided to the Funds by MML Investment Advisers, LLC.

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