Consolidated Statements of Assets and Liabilities (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024		Dec. 31, 2023
Investments, cost	$ 3,266,313	[1]	$ 3,038,208	[2]
Securities purchased under collateralized agreements to resell, cost	30,000		30,000
Deferred financing costs, accumulated amortization	$ 61,723		$ 54,263
Preferred stock, par value (in dollars per share)	$ 0.01		$ 0.01
Preferred stock, authorized (in shares)	2,000,000		2,000,000
Preferred stock, issued (in shares)	0		0
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock, authorized (in shares)	200,000,000		200,000,000
Common stock, issued (in shares)	107,851,415		102,558,859
Common stock, outstanding (in shares)	107,851,415		102,558,859
Non-controlled/Non-affiliated
Investments, cost	$ 2,459,913		$ 2,283,490
Non-controlled/Affiliated
Investments, cost	121,649	[3]	107,895	[4]
Controlled
Investments, cost	$ 684,751	[5]	$ 646,823	[6]

[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.

[3] Denotes a portfolio company of which the Company is an “Affiliated Person”, as defined in the Investment Company Act of 1940, as amended (the "1940 Act"), due to owning or holding the power to vote 5.0% or more of the outstanding voting securities of the investment but not controlling the company. Fair value as of September 30, 2024 and December 31, 2023, along with transactions during the nine months ended September 30, 2024 in which the issuer was a non-controlled/affiliated investment, is as follows: Portfolio CompanyFair Value at December 31, 2023Gross Additions (A)Gross Redemptions (B)Net Change In Unrealized Appreciation (Depreciation)Fair Value at September 30, 2024Net Realized Gains (Losses)Interest IncomeDividend IncomeOther IncomeEagle Infrastructure Services, LLC (fka FR Arsenal Holdings II Corp.) / Eagle Infrastructure Super HoldCo, LLC$17,873 $— $(50)$1,333 $19,156 $— $1,088 $— $— Sierra Hamilton Holdings Corporation2,000 — — — 2,000 — — — — TVG-Edmentum Holdings, LLC / Edmentum Ultimate Holdings, LLC113,786 13,804 — (35,729)91,861 — 2,685 4,211 188 Total Non-Controlled/Affiliated Investments$133,659 $13,804 $(50)$(34,396)$113,017 $— $3,773 $4,211 $188 

[4] Denotes investments in which the Company is an “Affiliated Person”, as defined in the Investment Company Act of 1940, as amended (the "1940 Act"), due to owning or holding the power to vote 5.0% or more of the outstanding voting securities of the investment but not controlling the company. Fair value as of December 31, 2023 and December 31, 2022 along with transactions during the year ended December 31, 2023 in which the issuer was a non-controlled/affiliated investment is as follows: Portfolio CompanyFair Value at December 31, 2022Gross
Additions
(A)Gross
Redemptions
(B)Net Change In Unrealized Appreciation (Depreciation)Fair Value at December 31, 2023Net 
Realized
Gains
(Losses)Interest
IncomeDividend
IncomeOther
IncomeEagle Infrastructure Services, LLC (fka FR Arsenal Holdings II Corp.) / Eagle Infrastructure Super HoldCo, LLC$— $15,581 $(459)$2,751 $17,873 $— $1,084 $— $— Sierra Hamilton Holdings Corporation4,000 2 (7)(1,995)2,000 — 2 — 1 TVG-Edmentum Holdings, LLC / Edmentum Ultimate Holdings, LLC126,787 6,807 — (19,808)113,786 — 3,048 4,625 250 Total Non-Controlled/Affiliated Investments$130,787 $22,390 $(466)$(19,052)$133,659 $— $4,134 $4,625 $251  (A)Gross additions include increases in the cost basis of investments resulting from new portfolio investments, payment-in-kind (“PIK”) interest or dividends, the amortization of discounts, reorganizations or restructurings and the movement of an existing portfolio company into this category from a different category. (B)Gross reductions include decreases in the cost basis of investments resulting from principal collections related to investment repayments or sales, reorganizations or restructurings and the movement of an existing portfolio company out of this category into a different category.

[5] Denotes portfolio companies which the Company "controls", as defined in the 1940 Act, due to owning or holding the power to vote more than 25.0% of the outstanding voting securities of the investment. Fair value as of September 30, 2024 and December 31, 2023, along with transactions during the nine months ended September 30, 2024 in which the issuer was a controlled investment, is as follows: Portfolio Company (1)Fair Value at December 31, 2023Gross Additions (A)Gross Redemptions (B)Net Change In Unrealized Appreciation (Depreciation)Fair Value at September 30, 2024Net Realized Gains (Losses)Interest IncomeDividend IncomeOther IncomeHaven Midstream LLC / Haven Midstream Holdings LLC / QID TRH Holdings LLC $3,419 $— $— $(2,765)$654 $3,895 $— $— $30 National HME, Inc./NHME Holdings Corp.3,000 — — — 3,000 — — — — New Benevis Topco, LLC / New Benevis Holdco, Inc.135,401 7,411 — (5,639)137,173 — 9,679 — 375 New Permian Holdco, Inc. / New Permian Holdco, L.L.C.63,170 5,637 — (5,999)62,808 — 4,010 — 375 NM APP Canada Corp.7 — — (7)— 31 — — — NM CLFX LP11,731 — — (1,700)10,031 — — 601 — NM NL Holdings, L.P.96,071 — (2,123)9,291 103,239 (548)— 6,133 181 NM GP Holdco, LLC1,048 — (11)612 1,649 (3)— 67 — NM YI LLC9,550 — — 411 9,961 — — 654 — NMFC Senior Loan Program III LLC140,000 20,000 — — 160,000 — — 17,204 — NMFC Senior Loan Program IV LLC112,400 — — — 112,400 — — 12,153 — UniTek Global Services, Inc.91,999 7,014 — 5,553 104,566 — 2,301 4,715 1,088 Total Controlled Investments$667,796 $40,062 $(2,134)$(243)$705,481 $3,375 $15,990 $41,527 $2,049 

[6] Denotes investments in which the Company is in “Control”, as defined in the 1940 Act, due to owning or holding the power to vote more than 25.0% of the outstanding voting securities of the investment. Fair value as of December 31, 2023 and December 31, 2022 along with transactions during the year ended December 31, 2023 in which the issuer was a controlled investment, is as follows: Portfolio CompanyFair Value at December 31, 2022Gross
Additions
(A)Gross
Redemptions
(B)Net Change In
Unrealized
Appreciation
(Depreciation)Fair Value at December 31, 2023Net Realized Gains (Losses)Interest
IncomeDividend
IncomeOther
IncomeHaven Midstream LLC / Haven Midstream Holdings LLC / QID TRH Holdings LLC $35,788 $— $— $(32,369)$3,419 $33,815 $— $— $2,041 National HME, Inc./NHME Holdings Corp.5,381 — (17,404)15,023 3,000 (17,404)— — — New Benevis Topco, LLC / New Benevis Holdco, Inc.114,146 26,153 — (4,898)135,401 — 11,632 — 1,500 New Permian Holdco, Inc. / New Permian Holdco, L.L.C.57,564 5,606 — — 63,170 — 5,197 — 506 NM APP CANADA CORP— — — 7 7 — — — — NM CLFX LP16,172 — (259)(4,182)11,731 — — 1,252 — NM NL Holdings, L.P.94,305 — — 1,766 96,071 — — 8,191 — NM GP Holdco, LLC1,028 — — 20 1,048 — — 88 — NM YI LLC9,481 — — 69 9,550 — — 853 — NMFC Senior Loan Program III LLC140,000 — — — 140,000 — — 20,038 — NMFC Senior Loan Program IV LLC112,400 — — — 112,400 — — 15,483 — UniTek Global Services, Inc.103,770 8,699 (26,446)5,976 91,999 2 4,000 5,303 1,268 Total Controlled Investments$690,035 $40,458 $(44,109)$(18,588)$667,796 $16,413 $20,829 $51,208 $5,315 
(A)Gross additions include increases in the cost basis of investments resulting from new portfolio investments, PIK interest or dividends, the amortization of discounts, reorganizations or restructurings and the movement of an existing portfolio company into this category from a different category. (B)Gross redemptions include decreases in the cost basis of investments resulting from principal collections related to investment repayments or sales, reorganizations or restructurings and the movement of an existing portfolio company out of this category into a different category.