Fund BBgBarc US Agg 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

Treasury 4.10 0.84 -0.82

CMBS 5.50 0.32 -0.72

ABS 15.90 -0.06 -1.69

MBS 17.74 0.24 0.17

RMBS 3.00 0.24 -0.18

HY - Credit 11.05 0.94 -0.48

IG - Credit 34.11 1.72 -0.83

Municipals 0.12 -0.03 0.02

Sovereign 0.88 0.05 -0.09

Other 5.21 0.38 0.32

Cash 2.40 -0.08 0.06

Quarterly Portfolio Commentary:

Phil Connor, CFA Investment DirectorInvestment Experience: 29 Years

HIGHLIGHTS• The Bloomberg Barclays U.S. Aggregate Bond Index rose by 2.9% inthe quarter.• While all sectors were positive, benchmark strength was led by thecorporate bond segment.• Allocation to credit sectors was positive for Fund performance.• Selection effects were mostly positive across corporate and securitizedsectors.

Fund Objective: This Fund seeks a superior total rate of return by investing in fixed income instruments.

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

I SHARE CLASS TICKER: MDBZX

As of 06/30/2020

MassMutual Premier Diversified Bond FundBarings LLC

Tre

asur

y

CM

BS

AB

S

MB

S

RM

BS

HY

- C

redi

t

IG -

Cre

dit

Mun

icip

als

Sov

erei

gn

Oth

er

Cas

h

0

10

20

30

40

Per

cent

of P

ortfo

lioP

erce

nt o

f Por

tfolio

Tre

asur

y

CM

BS

AB

S

MB

S

RM

BS

HY

- C

redi

t

IG -

Cre

dit

Mun

icip

als

Sov

erei

gn

Oth

er

Cas

h

-2

-1

0

1

2

Val

ue A

dded

vs.

Ben

chm

ark

(%)

Val

ue A

dded

vs.

Ben

chm

ark

(%)

Quarterly Portfolio Commentary:

Credit sectors rebounded in the quarter, following a sharp underperformance due to the economic shock from COVID-19 in the prior quarter. Investmentgrade corporate bonds fared well by posting a +8.47% excess return, leading benchmark performance. U.S. Treasury note yields dropped slightly. The 2-year note yield fell by 0.07% to 0.16%, while the 10-year note yield fell 0.04% to 0.66%. The U.S. Federal Reserve (the “Fed”) has substantially supportedthe bond market, including large scale purchases of U.S. Treasuries and U.S. Agency Mortgage Backed Securities (MBS). It also has bought AgencyCommercial MBS, credit related Exchange Traded Funds (ETFs) and some individual corporate bonds. Credit spread improvement across corporate bonds,commercial mortgage-backed security (CMBS), and asset-backed security (ABS) sectors within the benchmark is attributable to the Fed’s actions,combined with improvement in economic outlook. The one outlier in the quarter is Agency MBS, where investors assessed changes in cash flows fromrefinancing activity. The sector’s performance was still positive and ahead of U.S. Treasuries, but lagged other sectors. Outside the benchmark, inflation-protected securities exceeded nominal U.S. Treasuries. Also, U.S. High Yield and Emerging Market Debt indices were robust - over 10% for the former andover 9% for the latter.

The Fund had strong benchmark relative performance in the quarter, as well as among peer funds in the intermediate-core bond category. While theseresults were beneficial, relative year-to-date performance remains considerably below expectations stemming from impacts of the COVID-19 economicshock event of the first quarter. The Fund maintained, and enhanced in some cases, its primary credit exposures. This enabled performance to capitalizeon recovery in some of the poor performing positions from the prior quarter’s volatility. For instance, Fund composition in BBB credit was 35% of assets asof the end of June, compared to about 33% at March month end. Corporate BBB issues led this fixed income sector’s returns in the quarter, reflecting aforceful yield spread compression coinciding with the Fed’s policy movement in support of the sector. Below investment-grade corporate bond holdings,at a consistent weight to last quarter of just over 13% of Fund assets, were also a positive contributor to Fund performance. These issues generallyperformed well as a group and in excess of investment grade counterparts. Corporate industrial issues provided the largest positive impact, especiallythose in the oil & gas pipeline and broader energy industry. Elsewhere within the corporate segment, Fund allocation and selection among financial issuesalso delivered strong performance. The remaining large positive effect was the underweight allocation to U.S. Treasury instruments, an outcome of creditsectors being in relative favor in the quarter. The Fund’s commercial mortgage-backed security exposure and collateralized loan exposure also contributedamid the market’s positive tone.

Asset-backed security (ABS) exposure within the Fund had mixed results depending on issue type. Value recovery in the sector has been more gradual andless in magnitude in comparison to the corporate sector. ABS issues contributing positively from a selection attribution perspective were equipment andfranchise receivables. Other consumer loan collateral, such as student and automobile loan, also contributed positively but lagged the broader ABS sectorperformance of the benchmark. Weakness trended in some areas, such as auto rental structures, which declined in value and detracted. Aviation andtimeshare collateral structures had mixed issuer results. There was slight detraction overall from the sector. Management of ongoing credit risk is a priorityagainst the economic backdrop, however, has not led to substantial change in overall sector allocation.

TICKER: MDBZX Fund Inception: 5/3/1999Morningstar Category: Intermediate Core-Plus Bond

Average Annual Total Return

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

MassMutual Premier Diversified Bond I 7.31% 1.46% 4.64% 4.17% 3.77% 4.44%

BBgBarc US Agg Bond Index 2.90% 6.14% 8.74% 5.32% 4.30% 3.82%

Category Average Returns -- -- 6.83% 4.58% 3.98% 4.16%

Category Rank -- -- 83 71 67 31

# of Funds in Category -- -- 601 534 455 333Performance shown is for class I shares. Gross expenses = 0.55%, Net expense = 0.55%. Max Sales charge for I is 0.00%Performance shown is past performance. Past performance does not guarantee future results . You can lose money, including loss of pr incipal , by invest ing in this fund. Investors should careful ly consider investment objectives, r isks , 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 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. For more current information, including month-end performance, please cal l 1-866-444-2601. You cannot invest directly in an index. Issues rated AAA, AA, A and BBB are considered investment grade and anything below BBB is considered non-investment grade.Pre-Inception Returns - The inception date listed is that of the oldest share class of the Fund. Performance shown subsequent to the inception date

is the actual performance of the share class. Other share classes of the investment itself have existed longer, which accounts for any pre-inception performance shown. The pre-inception performance of Class I for the periods prior to its inception date of (12/03/2010) is based on the performance of an older share class, Class R5, using the expenses and fees of Class R5 (inception date 05/03/1999). If the expenses of the newer share class was used rather than the expenses of the old share class (due to lower expenses of the new share class), it would have resulted in better performance.The Fund’s Princ ipa l R isks include - Bank Loans Risk, Below Investment Grade Debt Securities Risk, Cash Position Risk, Convertible Securities Risk, Credit Risk, Defaulted and Distressed Securities Risk, Derivatives Risk, Dollar Roll and Reverse Repurchase Agreement Transaction 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- and Asset-Backed Secuirites Risk, Repurchase Agreement Risk, Restricted Securities Risk, Risk of Investment in Other Funds or Pools, Sector Risk, Sovereign Debt Obligations Risk, U.S. Government Securities Risk, Valuation Risk, When Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk. Please refer to the summary prospectus (a copy can be obtained by sending an email to fundinfo@massmutual.com) for more 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 same

category 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. © 2020 Morningstar, Inc. All Rights Reserved. The information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information.

MassMutual Premier Diversified Bond Fund

1

2

1

2

RS9093b RS-49229-01

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

THIS PAGE INTENTIONALLY LEFT BLANK