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


(in millions)	September 30, 2023		December 31, 2022
Marketable equity securities	$	407.3	$	279.5
Non-marketable equity securities		226.7		395.8
Equity method investments		74.7		78.9
	$	708.7	$	754.2

Investments in marketable equity securities are summarized as follows:


(in millions)	Cost		Unrealized losses			Estimated fair value
September 30, 2023
Common stocks	$	432.0	$	(36.0	)	$	396.0
Preferred stocks		15.3		(4.0	)		11.3
	$	447.3	$	(40.0	)	$	407.3
December 31, 2022
Common stocks	$	323.7	$	(55.6	)	$	268.1
Preferred stocks		15.3		(3.9	)		11.4
	$	339.0	$	(59.5	)	$	279.5

Net losses of $29.4 million and net gains of $20.5 million resulting from changes in the fair values of marketable equity securities were recognized for the three and nine months ended September 30, 2023, respectively, which included net unrealized losses of $32.2 million and net unrealized gains of $19.0 million on securities still held at September 30, 2023, respectively. Included in net losses/gains during the three and nine months ended September 30, 2023, were unrealized losses of $16.4 million and unrealized gains of $10.2 million, respectively, related to the Company's investment in Offerpad Solutions Inc. ("Offerpad"), a tech-enabled real estate company. Net losses of $49.8 million and $255.4 million resulting from changes in the fair values of marketable equity securities were recognized for the three and nine months ended September 30, 2022, respectively, which included net unrealized losses of $33.2 million and $231.4 million on securities still held at September 30, 2022, respectively. Included in net investment losses during the three and nine months ended September 30, 2022, were unrealized losses of $31.2 million and $166.8 million, respectively, related to the Company’s investment in Offerpad.

During the nine months ended September 30, 2023, the Company paid $25.0 million to purchase additional shares of Offerpad common stock. The cost and fair values of the Company’s investment in Offerpad at September 30, 2023 and December 31, 2022, totaled $110.0 million and $50.0 million and $85.0 million and $14.8 million, respectively.

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


(in millions)	Cost		Unrealized (losses) gains			Carrying amount
September 30, 2023	$	300.1	$	(73.4	)	$	226.7
December 31, 2022	$	307.2	$	88.6		$	395.8

The Company recognized unrealized losses and impairment charges totaling $122.4 million and $162.0 million for the three and nine months ended September 30, 2023, respectively, and unrealized losses and impairment charges totaling $119.9 million and $116.4 million during the three and nine months ended September 30, 2022, respectively, related to its investments in private venture-stage companies. All such unrealized losses related to securities still held at September 30, 2023 and 2022. Cumulative unrealized losses and impairment charges and cumulative unrealized gains related to the Company's non-marketable equity securities totaled $315.2 million and $241.8 million, respectively, at September 30, 2023, and $153.2 million and $241.8 million, respectively, at December 31, 2022.

Also, during the nine months ended September 30, 2022, the Company realized a gain of $51.1 million and cash proceeds of $63.0 million related to the sale of an investment in a title insurance business.