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


	December 31,
(in millions)	2022		2021
Marketable equity securities	$	280	$	657
Non-marketable equity securities		396		441
Equity method investments		78		78
	$	754	$	1,176

Investments in marketable equity securities are summarized as follows:


(in millions)	Cost		Unrealized gains (losses)			Estimated fair value
December 31, 2022
Common stocks	$	324	$	(55	)	$	269
Preferred stocks		15		(4	)		11
	$	339	$	(59	)	$	280
December 31, 2021
Common stocks	$	418	$	222		$	640
Preferred stocks		17		—			17
	$	435	$	222		$	657

Net losses of $263 million and net gains of $184 million resulting from changes in the fair values of marketable equity securities were recognized for the years ended December 31, 2022 and 2021, respectively, which included net unrealized losses of $237 million and net unrealized gains of $172 million on securities still held at December 31, 2022 and 2021, respectively. Included in net losses during the year ended December 31, 2022 and net gains during the year ended December 31, 2021 were unrealized losses of $191 million and unrealized gains of $121 million, respectively, related to changes in the fair value of the Company’s investment in Offerpad Solutions Inc., a tech-enabled real estate company, which began trading publicly in September 2021. Net gains and losses resulting from changes in the fair values of marketable equity securities are recognized in net investment gains/losses on the consolidated statements of income.

Investments in non-marketable equity securities are summarized as follows:


(in millions)	Cost		Unrealized gains		Carrying amount
December 31, 2022	$	307	$	89	$	396
December 31, 2021	$	215	$	226	$	441

The Company recognized unrealized losses of $153 million, which included impairment charges of $140 million and recognized unrealized gains of $16 million for the year ended December 31, 2022, all related to its investments in private venture-stage companies. For the year ended December 31, 2021, the Company recognized unrealized gains of $210 million related to its investments in private venture-stage companies. All such unrealized losses and gains related to securities still held at December 31, 2022 and 2021. Net gains and losses on non-marketable equity securities are recognized in net investment gains/losses on the consolidated statements of income.

Also, during the year ended December 31, 2022, the Company realized a gain of $52 million and cash proceeds of $63 million related to the sale of an investment in a title insurance business.