Consolidated Statements of Operations - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Jun. 30, 2023
Jun. 30, 2022
Investment income        
PIK interest income $ 7,867 $ 7,292 $ 16,890 $ 15,815
Non-cash dividend income 6,736 5,304 13,237 10,383
Total investment income 95,492 73,110 187,445 142,073
Expenses        
Interest and other financing expenses 31,700 20,672 62,496 39,309
Management fee 11,577 11,770 23,215 23,323
Incentive fee 9,982 7,926 19,579 15,403
Administrative expenses 953 932 2,001 2,141
Professional fees 1,003 817 1,968 1,754
Other general and administrative expenses 513 518 1,001 995
Total expenses 55,728 42,635 110,260 82,925
Less: management fee waived (See Note 5) (1,096) (1,142) (2,159) (2,234)
Less: expenses waived and reimbursed (See Note 5) 0 0 0 (238)
Net expenses 54,632 41,493 108,101 80,453
Net investment income before income taxes 40,860 31,617 79,344 61,620
Income tax expense (benefit) 932 (87) 1,028 8
Net investment income 39,928 31,704 78,316 61,612
Net realized gains (losses):        
Investments     3,231 35,690
Foreign currency 1 40 13 385
Net change in unrealized (depreciation) appreciation:        
Investments     (1,461) (42,707)
Securities purchased under collateralized agreements to resell (39) 0 (39) (2,021)
Foreign currency 29 (193) 55 (615)
Provision for taxes (94) (155) (225) (157)
Net realized and unrealized (losses) gains (4,850) (16,564) 1,574 (9,425)
Net increase in net assets resulting from operations 35,078 15,140 79,890 52,187
Less: Net (increase) decrease in net assets resulting from operations related to non-controlling interest in New Mountain Net Lease Corporation (248) 814 (487) (41)
Net increase (decrease) in net assets resulting from operations/ members capital $ 34,830 $ 15,954 $ 79,403 $ 52,146
Basic earnings per share (in dollars per share) $ 0.35 $ 0.16 $ 0.79 $ 0.52
Weighted average shares of common stock outstanding - basic (in shares) 100,937,026 100,596,188 100,937,026 99,510,862
Diluted earnings per share (in dollars per share) $ 0.32 $ 0.16 $ 0.71 $ 0.50
Weighted average shares of common stock outstanding - diluted (in shares) 127,016,910 113,853,773 125,313,634 112,768,447
Distributions declared per share (in dollars per share) $ 0.35 $ 0.30 $ 0.67 $ 0.60
Distributions paid per share (in dollars per share) $ 0.35 $ 0.30 $ 0.67 $ 0.60
Non-controlled/Non-affiliated        
Investment income        
Interest income (excluding Payment-in-kind ("PIK") interest income) $ 64,649 $ 41,089 $ 125,407 $ 78,533
PIK interest income 3,767 2,934 7,711 6,236
Dividend income 47 87 94 135
Non-cash dividend income 4,305 3,189 8,471 6,274
Other income 686 4,287 2,604 5,918
Net realized gains (losses):        
Investments (7,314) (594) (8,622) (664)
Net change in unrealized (depreciation) appreciation:        
Investments 2,174 (20,507) (755) (25,031)
Non-controlled/Affiliated        
Investment income        
Interest income (excluding Payment-in-kind ("PIK") interest income) 683 263 692 518
PIK interest income 414 258 1,105 509
Non-cash dividend income 1,139 1,012 2,244 1,994
Other income 63 62 126 125
Net change in unrealized (depreciation) appreciation:        
Investments 1 2,999 (15) 13,758
Controlled        
Investment income        
Interest income (excluding Payment-in-kind ("PIK") interest income) 1,243 1,715 2,687 3,371
PIK interest income 3,686 4,085 8,074 9,055
Dividend income 12,143 10,671 23,138 22,316
Non-cash dividend income 1,292 1,063 2,522 2,075
Other income 1,375 2,395 2,570 5,014
Net realized gains (losses):        
Investments 9,880 17,112 11,853 36,354
Net change in unrealized (depreciation) appreciation:        
Investments $ (9,488) $ (15,266) $ (691) $ (31,434)