MAIN Balance Sheet Summary LMM Portfolio Investments Middle Market Portfolio Investments $ 892,591 630,579 $ 886,559 568,796 $ 932,074 624,060 $ 938,042 607,476 $ 948,196 609,256 Private Loan Investments 342,867 384,220 379,809 485,929 467,474 Other Portfolio Investments External Investment Adviser Cash and Cash Equivalents 100,252 30,617 24,480 106,331 33,472 33,605 103,899 37,104 21,799 99,230 39,304 30,144 104,611 41,768 51,528 Other Assets 50,966 63,506 65,973 69,557 42,562 Total Assets Credit Facility $ 2,072,352 $ 2,076,489 $ 2,164,718 $ 2,269,682 $ 2,265,395 $ 343,000 $ 288,000 $ 303,000 $ 355,000 $ 64,000 SBIC Debentures(1) 235,686 239,355 255,663 269,345 288,483 Notes Payable 261,645 265,655 262,159 262,416 444,688 Other Liabilities Net Asset Value (NAV) 30,540 1,201,481 39,545 1,243,934 61,151 1,282,745 53,255 1,329,666 87,856 1,380,368 Total Liabilities and Net Assets Total Portfolio Fair Value as % of Cost Common Stock Price Data: $ 2,072,352 $ 2,076,489 $ 2,164,718 $ 2,269,682 $ 2,265,395 107% 105% 105% 106% 108% High Close Low Close Quarter End Close $ 37.36 32.23 36.77 $ 38.27 35.39 38.27 $ 40.39 37.80 38.46 $ 40.40 38.13 39.75 $ 41.55 39.71 39.73 (1) Includes adjustment to the face value of Main Street Capital II, LP (MSC II) Small Business Investment Company (SBIC) debentures pursuant to the fair value method of accounting elected for such MSC II SBIC borrowings. Total par value of SBIC debentures at December 2017 was $295.8 million. Main Street Capital Corporation NYSE: MAIN mainstcapital.com Page 39 ($ in 000's, except per share amounts) Q4 16 Q1 17 Q2 17 Q3 17 Q4 17