HOUSTON, Feb. 3, 2011 /PRNewswire/ -- Main Street Capital Corporation (NYSE: MAIN) ("Main Street") announced today that it has completed a new portfolio investment totaling $7.5 million in invested capital.

Main Street's investment in Principle Environmental, LLC ("Principle" or the "Company") supported the recapitalization of the Company, as well as provided additional financing for future growth. The Principle investment consists of $5.5 million in first lien secured debt with equity warrant participation and a $2.0 million direct equity investment. Headquartered in Weatherford, Texas with additional facilities in Pennsylvania, the Company provides comprehensive noise mitigation solutions including the design and installation of acoustical sound control systems along with noise measurement, monitoring and analysis services. The Company primarily serves the oil and gas and transportation industries, and is the leading provider of noise abatement services in the Marcellus Shale oil and gas basin. Principle will continue to be led by its President, Larson Hampton, and Vice President, Bill Martin.

ABOUT MAIN STREET CAPITAL CORPORATION

Main Street (www.mainstcapital.com) is a principal investment firm that primarily provides long-term debt and equity capital to lower middle market companies. Main Street's lower middle market 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 within its lower middle market portfolio. Main Street also maintains a portfolio of privately placed secured, interest-bearing debt investments in middle market businesses that are generally larger in size than its lower middle market portfolio companies.

Contacts:
Main Street Capital Corporation
Todd A. Reppert, President and CFO
treppert@mainstcapital.com
713-350-6000
Dennard Rupp Gray & Lascar, LLC
Ken Dennard  |  ksdennard@drg-l.com
Ben Burnham |  bburnham@drg-l.com
713-529-6600

SOURCE Main Street Capital Corporation

For further information: Todd A. Reppert, President and CFO of Main Street Capital Corporation, +1-713-350-6000, treppert@mainstcapital.com; or Ken Dennard, ksdennard@drg-l.com, or Ben Burnham, bburnham@drg-l.com, both of Dennard Rupp Gray & Lascar, LLC, +1-713-529-6600, for Main Street Capital Corporation