Investments in equity securities, by accounting classification, are summarized as follows:


(in millions)	September 30, 2026		December 31, 2025
Marketable equity securities	$	505.4	$	477.6
Non-marketable equity securities		216.6		253.1
Equity method investments		146.1		118.4
	$	868.1	$	849.1

Investments in marketable equity securities are summarized as follows:


(in millions)	Cost		Unrealized gains		Estimated fair value
September 30, 2026
Common stocks	$	457.5	$	38.1	$	495.6
Preferred stocks		8.6		1.2		9.8
	$	466.1	$	39.3	$	505.4
December 31, 2025
Common stocks	$	457.9	$	9.8	$	467.7
Preferred stocks		9.0		0.9		9.9
	$	466.9	$	10.7	$	477.6

Net gains of $1.2 million and $41.5 million resulting from changes in the fair values of marketable equity securities were recognized for the three and nine months ended September 30, 2026, respectively, which included net unrealized gains of $1.2 million and $38.8 million on securities still held at September 30, 2026, respectively. Net gains of $38.7 million and $57.8 million resulting from changes in the fair values of marketable equity securities were recognized for the three and nine months ended September 30, 2025, respectively, which included net unrealized gains of $35.7 million and $55.0 million on securities still held at September 30, 2025, respectively.

A summary of the changes in the carrying amounts of non-marketable equity securities, which primarily relate to the Company's venture investment portfolio, for the three and nine months ended September 30, 2026 and 2025, is as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
(in millions)	2026			2025			2026			2025
Carrying amount, beginning of period	$	214.4		$	218.3		$	253.1		$	202.4
Net additions		2.7			16.0			7.1			31.2
Gross unrealized gains		0.3			1.0			0.7			2.5
Gross unrealized losses and impairments		(0.8	)		(3.9	)		(44.3	)		(4.7	)
Carrying amount, end of period	$	216.6		$	231.4		$	216.6		$	231.4

During the nine months ended September 30, 2026, the Company recorded an impairment loss of $41.7 million on a non-marketable equity investment resulting from an internal valuation, which was driven by a change in the operations of the underlying business.

Cumulative gross unrealized gains and cumulative gross unrealized losses and impairments related to non-marketable equity securities at September 30, 2026 and December 31, 2025, are summarized as follows:


(in millions)	September 30, 2026		December 31, 2025
Cumulative gross unrealized gains	$	280.8	$	280.1
Cumulative gross unrealized losses and impairments	$	405.1	$	360.8

Included in equity method investments are certain investments in nonconsolidated variable interest entities that are primarily limited partnerships. As of September 30, 2026 and December 31, 2025, the carrying values of these investments were $112.8 million and $86.8 million. At September 30, 2026, the Company’s maximum exposure to loss related to these investments, including any future commitments, was $125.4 million. In September 2026, the Company entered into a financing arrangement with an affiliated entity whereby it advanced $19.0 million, with optional advances up to a maximum of $25.0 million, in exchange for a secured promissory note with a term of 6 years and a stated interest rate of 11.0% per annum. The note is collateralized by first priority interests in multiple affiliated entities and is included in other assets on the condensed consolidated balance sheets.