Golub Capital BDC, Inc. is an externally managed, closed-end investment company that operates as a business development company, generating current income and capital appreciation by investing primarily in unitranche loans and other senior secured loans to U.S. middle-market companies, with selective positions in second lien loans, subordinated debt, warrants, and minority equity investments. The company typically deploys capital in investments of $10 million to $85 million per position, leveraging Golub Capital's extensive loan origination relationships and underwriting expertise to identify borrowers with recurring revenue models and strong customer retention. Revenue is derived principally from interest and origination fees on debt investments, capital gains on equity positions, and distributions from realizations, with the company using leverage through credit facilities and securitizations to enhance returns on its diversified portfolio of middle-market investments.