As of December 31, 2018, Ares Capital Corporation's ("Ares Capital" or "ARCC") portfolio had a fair value of approximately $12.4 billion, and consisted of 344 portfolio companies backed by 167 different private equity sponsors. Ares Capital has a diversified portfolio in terms of issuer concentration, asset class, industry sector and geographic representation.
(1) At fair value.
(2) Represents ARCC's portion of its co-investments with Varagon Capital Partners and its clients in first lien senior secured loans to U.S. middle-market companies. As of December 31, 2018, the Senior Direct Lending Program, LLC (the "SDLP") had loans to 21 different borrowers. The portfolio companies in the SDLP are in industries similar to companies in ARCC's portfolio.
(3) Includes ARCC's investment in the SDLP, which represented 5% of the total investment portfolio at fair value as of December 31, 2018.