Trailing Returns:

Average Annual Total Return

QTD YTD 1Y 3Y 5Y 10Y

MassMutual Select EquityOpports R5

-0.95 -0.95 13.42 9.65 12.53 11.93

Russell 1000 TR USD -0.69 -0.69 13.98 10.39 13.17 9.61

Category Average Return - - 12.82 8.89 11.72 8.58

Category Rank - - 50 42 41 1

# Funds in Category - - 1401 1204 1077 802

Performance shown is for class R5 shares. Current performance may be higher orlower. Max Sales charge for R5 is 0%.

Growth of $10,000:

Performance shown is for class R5 shares. Current performance may be higher orlower. Max Sales charge for R5 is 0%.

ConsumerDiscretionary 11.88%

Consumer Staples 13.53%

Energy 3.29%

Financials 20.38%

Healthcare 14.38%

Industrials 12.52%

InformationTechnology 10.75%

Materials 3.86%

Real Estate 5.18%

TelecommunicationServices 0.89%

Utilities 1.93%

Sector Allocation:Calendar Year Returns:

Performance shown is for class R5 shares. Current performance may be higher orlower. Max Sales charge for R5 is 0%.

Asset Allocation:

Cash 1.42%

US Equity 87.66%

Non-US Equity 10.93%

Other 0.00%

# of Stock Holdings 65

Overview:The investment seeks to achieve long-term capital appreciation primarily through investment in a portfolio of common stocks of establishedcompanies.Morningstar Category: US Fund Large Blend Fund Net Assets: $658M Fund Inception Date: 04/28/2000

Performance data given represents past performance and does not guarantee future results. Current performance may be lower or higher thanreturn data quoted herein. For more current information, including month-end performance, please call 1-866-444-2601. The investment returnand the principal value of an investment will fluctuate; so an investor's shares, when redeemed, may be worth more or less than their original cost.Investment portfolio statistics change over time. Returns shown do not reflect the impact of plan fees, which will reduce performance. Investmentportfolio statistics change over time.Pre-Inception Returns-The inception date listed is that of the oldest share class of the Fund. The inception date for each individual share class can be found onpage 2. Performance shown subsequent to the inception date is the actual performance of the share class. Other share classes of the investment itself (depending uponthe investment) may have existed longer, which may account for any pre-inception performance shown. If pre-inception performance is shown, it is generally theperformance of an older share class of the investment itself (depending upon the investment) adjusted for fees and expenses of the newer share class. However, ifusing the expenses of the newer share class rather than the expenses of the older share class (due to lower expenses of the newer share class) would result in betterperformance, then pre-inception performance represents that of the older share class without any expense adjustment.Performance-Returns reflect performance of the investment without adjusting for sales charges or the effects of taxation, but is adjusted to reflect all actual ongoinginvestment expenses and assumes reinvestment of dividends and capital gains (if applicable). If adjusted, sales charges would reduce the performance quoted. Inaddition, due to market volatility, performance may vary greatly over short periods of time. The investment's performance is generally compared with that of anindex. The index is an unmanaged portfolio of specified securities and does not reflect any initial or ongoing expenses nor can it be invested in directly. Aninvestment’s portfolio may differ significantly from the securities in the index. The Index may not be the same as the comparative index noted in the investment’sprospectus (if applicable).Growth of $10,000 Graph-The Growth of $10,000 graph shows an investment’s performance based on how $10,000 invested in the investment would have grownover time. The growth of $10,000 begins at the investment’s inception date or the first year listed on the graph, whichever is appropriate.

NOT FDIC INSURED - MAY LOSE VALUE - NO BANK GUARANTEE

MassMutual Select Equity Opportunities FundWellington Management Company LLP, T. Rowe Price Associates, Inc.

I: MFVZX R5: MFVSX SVC: MMFYX ADM: MMFVX R4: MFVFX A : MFVAX R3: MFVNX

AS OF 03/31/2018

Fund Performance Over 10 YearsFund Performance Over 10 Years

20072008

20092010

20112012

20132014

20152016

20172018

$6,383

$10,000

$16,000

$22,000

$28,000$31,167

Fund Russelll 1000

20102011

20122013

20142015

20162017

-9%

1%

11%

21%

31%

Top 10 Holdings:

Microsoft Corp 4.47%

Nike Inc B 3.98%

TJX Companies Inc 3.62%

Chubb Ltd 3.31%

Public Storage 3.19%

Canadian National Railway Co 3.17%

Bristol-Myers Squibb Company 3.04%

PNC Financial Services Group Inc 3.00%

Medtronic PLC 2.95%

American Express Co 2.92%

Risk Statistics:

FUND BENCHMARK

Standard Deviation 13.57 9.89

Alpha -3.43 0.00

Beta 1.26 1.00

R2 84.26 1.00

Tracking Error 5.96 0.00

Sharpe Ratio 0.92 1.28

Upside Capture 115.02 100.00

Downside Capture 143.10 100.00

Batting Average 51.67 -

Expense Ratios:

INCEPTION DATE GROSS EXPENSE NET EXPENSE

I 11/15/2010 0.74% 0.74%

R5 04/28/2000 0.84% 0.84%

Svc 04/28/2000 0.94% 0.94%

Admin 04/28/2000 1.04% 1.04%

A 04/01/2014 1.19% 1.19%

R4 05/01/2000 1.29% 1.29%

R3 12/30/2002 1.44% 1.44%

Portfolio Managers:

Managed Since

Donald J. KilbrideWellington Management Company LLP Mar. 2017

John D. Linehan, CFAT. Rowe Price Associates, Inc. Mar. 2017

Fund Rankings:

Overall Rating 3 Year 5 Year 10 Year

MorningstarRatingTM

Share Class R5 R5 R5 R5

Funds InCategory 1,401 1,204 1,077 802

Morningstar Rating™ Category-Large Blend. For each investment with at least a three-year history, Morningstar calculates a MorningstarRating™ based on how an investment ranks on a Morningstar Risk-Adjusted Return measure against other investments in the category. Thismeasure takes into account variations in an investment’s monthly performance after adjusting for sales loads (except for load-waived A shares), redemption fees, andthe risk-free rate, placing more emphasis on downward variations and rewarding consistent performance. The top 10% of investments in each category receive 5stars, the next 22.5% receive 4 stars, the next 35% receive 3 stars, the next 22.5% receive 2 stars and the bottom 10% receive 1 star. The Overall MorningstarRating for an investment is derived from a weighted average of the ratings for the three-, five- and ten-year (if applicable) time periods. The Morningstar percentileranking is based on the fund’s total-return percentile rank relative to all funds that have the same category for the same time 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 notadjusted for sales charges. © 2018 Morningstar, Inc. All Rights Reserved. The information contained herein: (1) is proprietary to Morningstar and/or its contentproviders; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers areresponsible for any damages or losses arising from any use of this informationInvestment Risks-The Fund’s Principal Risks include- Cash Position Risk, Convertible Securities Risk, Foreign Investment Risk; Emerging Markets Risk; CurrencyRisk, Liquidity Risk, Management Risk, Market Risk, Non-Diversification Risk, Preferred Stock Risk, Smaller 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 information on thespecific risks.Risk Statistics-Alpha is a measure of the difference between a fund’s actual returns and its expected performance, given its level of risk as measured by beta. Apositive alpha figure indicates the fund has performed better than its beta would predict. In contrast, a negative alpha indicates the fund’s underperformance, giventhe expectations established by the fund’s beta.Beta is a measure of sensitivity to market movements. The beta of the market is 1.00. A beta of 1.10 shows that thefund’s excess return is expected to be 10% better than the market’s excess return in an up market or 10% worse in a down market. A beta of .85 indicates that thefund’s excess return is expected to perform 15% less than the market’s excess return during up markets and 15% greater during down markets. Standard Deviation isa statistical measurement, which for a mutual fund depicts how widely the returns varied over a certain period of time. When a fund has a high standard deviation,performance is wide, implying greater volatility. R-squared (R2) measures the degree of relationship between the performance of the fund and that of the index. Thehigher the R- squared, the more related the fund’s performance is to its index.Tracking Error is also known as active risk and is the degree to which the strategydiffered from its index or benchmark. The higher the Tracking Error, the more the fund deviated from its index. Sharpe Ratio measures risk adjusted performance; itis calculated as the real total return of the fund (total return-risk free rate) divided by the risk of the fund (standard deviation). Upside/downside capture showswhether a given fund has outperformed--gained more or lost less than--a broad market benchmark during periods of market strength and weakness, and if so, by howmuch. An upside capture ratio over 100 indicates a fund has generally outperformed the benchmark during periods of positive returns for the benchmark. A downsidecapture ratio of less than 100 indicates that a fund has lost less than its benchmark in periods when the benchmark has been in the red. Batting Average is a measureof a manager’s ability to consistently beat its benchmark over the trailing five-year period.© 2018 Massachusetts Mutual Life Insurance Company (MassMutual), Springfield, MA. All rights reserved. www.massmutual.com. Principal Underwriter: MMLDistributors, 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.Investors should consider an investment option’s objectives, risks, fees, and expenses carefully before investing. This and other information can befound in the applicable prospectuses or summary prospectuses, which are available from MassMutual by calling 1-866-444-2601. Please read themcarefully before investing.RS-40715-01

NOT FDIC INSURED - MAY LOSE VALUE - NO BANK GUARANTEE

MassMutual Select Equity Opportunities Fund AS OF 03/31/2018

Past performance does not guarantee future results. You can lose money, including loss of principal, by investing in this fund. Investors should carefully consider investment objectives, risks, charges and expenses. This and other important information is contained in the fund prospectuses and summary prospectuses, which can be obtained from www.massmutualfunds.com and should be read carefully before investing. A list of the Fund’s holdings can also be obtained from www.massmutualfunds.com. These materials and the platform of investments made available by MassMutual are offered without regard to the individualized needs of any plan, its participants, or beneficiaries. These materials are not intended as impartial investment advice or to give advice in a fiduciary capacity to any plan. © 2018 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.

RS-41556-05

Quarterly Due Diligence Investment Commentary

AS OF 3/31/2018

MassMutual Select Equity Opportunities Fund T. Rowe Price Associates, Inc. / Wellington Management Company LLP

NOT FDIC INSURED - MAY LOSE VALUE - NO BANK GUARANTEE

Fund Overview

Select Equity Opportunities Fund is subadvised by T. Rowe Price Associates, Inc. (T. Rowe Price) and Wellington Management Company LLP (Wellington). The Fund is designed to take advantage of two concentrated managers focused on delivering alpha. Wellington portfolio manager Donald Kilbride has a disciplined style that focuses on companies he considers to be “durable franchises” that compound the growth of capital and distribute that growth back to shareholders over time. T. Rowe Price portfolio manager John Linehan is a contrarian value investor with preference for quality businesses at attractive relative valuations. The combination of the two is designed to remain in the Large Blend style box.

Volatility returned to the market as geopolitical tensions and global trade overshadowed corporate earnings.

The information technology and consumer discretionary sectors were top performers for the benchmark.

Fund performance narrowly lagged the index. Stock selection gains offset sector allocation decisions – most notably, the Fund’s nearly 14% underweight in the information technology sector.

Quarterly Market Commentary

After a strong January, the S&P 500® Index delivered negative returns in February and March, closing the first quarter of 2018 in negative territory for the first time in 10 quarters. The first quarter of 2018 saw the return of volatility, which lingered at all-time lows throughout 2017. This volatility spiked on fear of trade wars, higher interest rates, and increasing inflation. In this environment, emerging-market equities outpaced their domestic counterparts. From a style perspective, growth stocks outpaced value stocks across the market cap spectrum. Declines occurred across the market breadth as nine out of 11 equity sectors posted negative returns. Negative performance also spanned up and down the market cap spectrum, as large-cap stocks finished in line with mid-caps but lagged small-cap stocks.

Performance Drivers

Stock selection was most favorable within the consumer staples, energy, and real estate sectors. One common theme across all three sectors is that they each lagged the index by more than 5%, but positive stock selection provided much-needed downside protection in the volatile market environment. Costco Wholesale was the top performer within the consumer staples sector, outperforming the sector by more than 8%. Total (+4%) and Hess (+7%) were the top contributors within the energy sector, and all three holdings within the real estate sector outperformed the sector index return of -6%. Microsoft, Nike, and TJX were the top contributors to Fund performance. Some of the more cyclical stocks – such as UPS (-11%), Canadian National Railway (-11%), and DowDuPont (-10%) – were also among the notable names that detracted from Fund performance. While specific holdings within sectors supported returns, overall sector allocation decisions negatively affected performance. An underweight position in the information technology sector, combined with an overweight position to the poorly performing consumer staples sector, dragged on performance. Wellington exited its position in Merck, initiated a position in American Tower, and added to the Fund’s existing stake in Pepsi. T. Rowe Price sold Exelon and initiated a new position in Sempra Energy. The portfolio ended the quarter overweight in consumer staples (+6%), financials (+5%), and industrials (+2%), while underweight in information technology (-14%) and energy (-2%).

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