MassMutual Participation Investors is a closed-ended fixed income mutual fund launched and managed by Babson Capital Management LLC. The fund invests in the fixed income markets of the United States. It typically invests in below-investment grade, long-term corporate debt obligations which are directly purchased from its issuers. The fund also seeks to invest in warrants, conversion rights, or other equity related instruments. It benchmarks the performance of its portfolio against Standard and Poor's Industrials Composite, Russell 2000 Index, Lehman Brothers U.S. High Yield Index, and Lehman Brothers Intermediate U.S. Credit Index. MassMutual Participation Investors was formed on April 7, 1988 and is domiciled in the United States.