HOUSTON, Dec. 1, 2011 /PRNewswire/ -- Main Street Capital Corporation (NYSE: MAIN) ("Main Street") announced today that it has completed two new lower middle market portfolio investments totaling $8.2 million in invested capital. Main Street recently closed a $4.2 million investment in Radial Drilling Services Inc. ("RDS"). Main Street's investment in RDS consists of $4.2 million in first lien secured debt with equity warrant participation. The Main Street secured debt facility with RDS also provides for additional funding capacity, subject to certain conditions, beyond the initial $4.2 million investment to support future growth initiatives. Headquartered in Houston, Texas with branch offices in Russia and Canada, RDS is a provider of patented technologies, equipment and personnel to increase production in mature oil and gas wells using radial drilling through modified coiled tubing technology. Main Street's initial $4.2 million investment provides RDS with growth financing to develop new radial drilling units, further the technological capabilities, and expand its geographic coverage. Main Street also recently closed a $4.0 million investment to support the acquisition of SAMBA Holdings, Inc. ("SAMBA") by SAMBA's existing management team and a group of private investors. Main Street's $4.0 million investment consists of $3.0 million in first lien secured debt and a $1.0 million direct equity investment. Founded in 1998, SAMBA is headquartered in Albuquerque, New Mexico and is a leading provider of fleet compliance software and services to car and truck fleet owners. 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, interest-bearing debt investments in middle market businesses that are generally larger in size than its lower middle market portfolio companies.