v3.26.3
Investments - Investment Cost and Fair Value by Type and by Industry (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Schedule of Investments [Line Items]    
Cost $ 2,453,990 [1] $ 2,912,115 [2]
Fair Value 2,259,962 [1] 2,742,013 [2]
Business Services    
Schedule of Investments [Line Items]    
Cost 521,261 573,549
Fair Value 476,150 516,701
Software    
Schedule of Investments [Line Items]    
Cost 405,342 533,638
Fair Value 376,858 526,440
Healthcare    
Schedule of Investments [Line Items]    
Cost 394,706 517,598
Fair Value 363,588 463,591
Investment Funds (includes investments in joint ventures)    
Schedule of Investments [Line Items]    
Cost 275,632 275,632
Fair Value 260,701 275,677
Consumer Services    
Schedule of Investments [Line Items]    
Cost 145,272 193,415
Fair Value 140,394 192,842
Financial Services & Technology    
Schedule of Investments [Line Items]    
Cost 131,318 165,745
Fair Value 136,281 172,215
Net Lease    
Schedule of Investments [Line Items]    
Cost 80,336 81,370
Fair Value 121,149 115,127
Education    
Schedule of Investments [Line Items]    
Cost 200,836 195,960
Fair Value 118,364 118,507
Distribution & Logistics    
Schedule of Investments [Line Items]    
Cost 114,058 162,382
Fair Value 100,692 158,599
Packaging    
Schedule of Investments [Line Items]    
Cost 89,951 76,052
Fair Value 84,036 75,324
Energy    
Schedule of Investments [Line Items]    
Cost 80,332 75,771
Fair Value 69,283 65,833
Food & Beverage    
Schedule of Investments [Line Items]    
Cost   21,193
Fair Value   21,177
Business Products    
Schedule of Investments [Line Items]    
Cost   15,897
Fair Value   16,026
Consumer Products    
Schedule of Investments [Line Items]    
Cost 14,946 14,283
Fair Value 12,466 14,283
Specialty Chemicals & Materials    
Schedule of Investments [Line Items]    
Cost   9,630
Fair Value   9,671
First lien    
Schedule of Investments [Line Items]    
Cost 1,500,316 1,854,022
Fair Value 1,430,905 1,818,215
Second lien    
Schedule of Investments [Line Items]    
Cost 83,849 104,890
Fair Value 68,064 91,179
Subordinated    
Schedule of Investments [Line Items]    
Cost 101,477 128,705
Fair Value 101,722 121,487
Structured Finance Obligations    
Schedule of Investments [Line Items]    
Cost 3,232 3,232
Fair Value 3,217 3,277
Equity and other    
Schedule of Investments [Line Items]    
Cost 765,116 821,266
Fair Value $ 656,054 $ 707,855
[1] New Mountain Finance Corporation (the "Company") generally acquires its investments in private transactions exempt from registration under the Securities Act of 1933, as amended (the "Securities Act"). These investments are generally subject to certain limitations on resale, and may be deemed to be "restricted securities" under the Securities Act.
[2] New Mountain Finance Corporation (the "Company") generally acquires its investments in private transactions exempt from registration under the Securities Act of 1933, as amended (the "Securities Act"). These investments are generally subject to certain limitations on resale, and may be deemed to be "restricted securities" under the Securities Act.