Main Street Capital Added to Russell Microcap Index

HOUSTON, July 1 /PRNewswire-FirstCall/ -- Main Street Capital Corporation (Nasdaq: MAIN) ("Main Street") announced today that it was added to the Russell Microcap(R) Index when Russell Investments reconstituted its comprehensive family of U.S. indexes on June 27, 2008.

The Russell Microcap Index measures the performance of the microcap segment of the U.S. equity market. Membership in the Russell Microcap, which remains in place for one year, means automatic inclusion in the appropriate growth and value style indexes. Russell determines membership for its equity indexes primarily by objective, market-capitalization rankings and style attributes.

Annual reconstitution of Russell indexes captures the 4,000 largest U.S. stocks as of the end of May, ranking them by total market capitalization to create the Russell 3000(R) Index and Russell Microcap.

ABOUT MAIN STREET CAPITAL CORPORATION

Main Street (http://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 generally 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 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.

     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 July 1, 2008