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


(in millions)	June 30, 2026		December 31, 2025
Marketable equity securities	$	494.5	$	477.6
Non-marketable equity securities		214.4		253.1
Equity method investments		146.8		118.4
	$	855.7	$	849.1

Investments in marketable equity securities are summarized as follows:


(in millions)	Cost		Unrealized gains		Estimated fair value
June 30, 2026
Common stocks	$	447.7	$	37.0	$	484.7
Preferred stocks		8.6		1.2		9.8
	$	456.3	$	38.2	$	494.5
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 $49.8 million and $40.3 million resulting from changes in the fair values of marketable equity securities were recognized for the three and six months ended June 30, 2026, respectively, which included net unrealized gains of $47.2 million and $37.6 million on securities still held at June 30, 2026, respectively. Net gains of $26.1 million and $19.1 million resulting from changes in the fair values of marketable equity securities were recognized for the three and six months ended June 30, 2025, respectively, which included net unrealized gains of $26.0 million and $19.3 million on securities still held at June 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 six months ended June 30, 2026 and 2025, is as follows:


	Three Months Ended June 30,					Six Months Ended June 30,
(in millions)	2026			2025		2026			2025
Carrying amount, beginning of period	$	257.6		$	216.6	$	253.1		$	202.4
Net additions (transfers)		(0.6	)		0.2		4.4			15.2
Gross unrealized gains		0.4			1.5		0.4			1.5
Gross unrealized losses and impairments		(43.0	)		—		(43.5	)		(0.8	)
Carrying amount, end of period	$	214.4		$	218.3	$	214.4		$	218.3

During the three months ended June 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 recent 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 June 30, 2026 and December 31, 2025, are summarized as follows:


(in millions)	June 30, 2026		December 31, 2025
Cumulative gross unrealized gains	$	280.5	$	280.1
Cumulative gross unrealized losses and impairments	$	404.3	$	360.8