Main Street Capital Set to Join Russell 3000(R) Index

Indicates Automatic Inclusion in Widely Followed Russell 2000(R) Index

HOUSTON, June 16 /PRNewswire-FirstCall/ -- Main Street Capital Corporation (Nasdaq: MAIN) ("Main Street") announced today that it is set to join the broad-market Russell 3000(R) Index when Russell Investments ("Russell") reconstitutes its comprehensive set of U.S. and global equity indexes on June 26, 2009, according to a preliminary list of additions posted on June 12, 2009 at www.russell.com. Inclusion in the Russell 3000 Index indicates that Main Street, based upon its total market capitalization, will also automatically be included in the widely followed Russell 2000(R) Index for U.S. small-cap stocks.

The annual reconstitution of Russell's U.S. indexes captures the 4,000 largest U.S. stocks as of the end of May, ranking them by total market capitalization. Membership in the Russell 3000 Index, which remains in place for one year, means automatic inclusion in the large-cap Russell 1000(R) Index or small-cap Russell 2000 Index, as well as the appropriate growth and value style indexes. Russell determines membership for its equity indexes primarily by objective, market-capitalization rankings and style attributes. The Russell 3000 Index also serves as the U.S. component of the Russell Global(R) Index, which Russell launched in 2007. The Russell indexes are widely used by investment managers and institutional investors for index funds and as benchmarks for both passive and active investment strategies. An industry-leading $4 trillion in assets currently are benchmarked to them.

Total returns data for the Russell 3000 Index and the Russell Global Index, as well as other Russell Indexes, is available at www.russell.com/Indexes/performance/default.asp.

ABOUT MAIN STREET CAPITAL CORPORATION

Main Street (www.mainstcapital.com) is a principal investment firm that provides long-term debt and equity capital to lower middle market companies. Main Street's investments are made to support management buyouts, recapitalizations, growth financings and acquisitions of companies that operate in diverse industry sectors and generally have annual revenues ranging from $10 million to $100 million. Main Street seeks to partner with entrepreneurs, business owners and management teams and generally provides "one stop" financing alternatives to its portfolio companies.

Forward-Looking Statements

This press release may contain forward-looking statements. Words such as "estimates", "expects", "expected", "believes", and "future" or similar expressions are intended to identify forward-looking statements. Any such statements, other than statements of historical fact, may be affected by other unknowable future events and conditions, including elements of the future that are not under Main Street's control, or factors that Main Street may not have considered; accordingly, such statements are not guarantees or assurances of any aspect of future performance. Actual developments and results may vary materially from these forward-looking statements. Such statements speak only as of the time when made, and Main Street undertakes no obligation to update any such statement now or in the future.

    Contacts:
    Main Street Capital Corporation
    Todd A. Reppert, President and CFO
    treppert@mainstcapital.com
    713-350-6000

    Dennard Rupp Gray and Easterly, LLC
    Ken Dennard
    ksdennard@drg-e.com / 713-529-6600
    Augustine Okwu
    gokwu@drg-e.com / 404-532-0086

SOURCE Main Street Capital Corporation

Released June 16, 2009