Schedule of gross unrealized gains and losses, and the amortized cost, allowance for credit losses, and fair value of those investments classified as available-for-sale

The amortized cost, gross unrealized gains and losses, fair value of those investments classified as available-for-sale, and allowance for credit losses at September 30, 2023 are summarized as follows (in thousands):


	September 30, 2023
	Amortized		Gross		Gross		Fair		Allowance for
	Cost		Unrealized Gains		Unrealized Losses		Value		Credit Losses
Corporate bonds	$	128,111	$	—	$	—	$	128,111		—
U.S. Treasuries		260,657		—		—		260,657		—
Total	$	388,768	$	—	$	—	$	388,768	$	—

The amortized cost, gross unrealized gains and losses, fair value of those investments classified as available-for-sale, and allowance for credit losses at December 31, 2022 are summarized as follows (in thousands):


	December 31, 2022
	Amortized		Gross		Gross		Fair		Allowance for
	Cost		Unrealized Gains		Unrealized Losses		Value		Credit Losses
Corporate bonds	$	200,735	$	7	$	(7,109)	$	193,633		—
U.S. Treasuries		1,154,879		111		(15,680)		1,139,310		—
Total	$	1,355,614	$	118	$	(22,789)	$	1,332,943	$	—

Schedule of investments classified as equity securities

The cost, gross unrealized gains and losses, and fair value of those investments classified as equity securities at September 30, 2023 are summarized as follows (in thousands):


	September 30, 2023
			Gross		Gross		Fair
	Cost		Unrealized Gains		Unrealized Losses		Value
Fixed income mutual funds	$	70,257	$	—	$	(2,434)	$	67,823
Total	$	70,257	$	—	$	(2,434)	$	67,823

The cost, gross unrealized gains and losses, and fair value of those investments classified as equity securities at December 31, 2022 are summarized as follows (in thousands):


	December 31, 2022
			Gross		Gross		Fair
	Cost		Unrealized Gains		Unrealized Losses		Value
Fixed income mutual funds	$	70,257	$	—	$	(2,620)	$	67,637
Exchange traded mutual funds		75,999		—		(8,800)		67,199
Total	$	146,256	$	—	$	(11,420)	$	134,836

Summary of investments under the equity method

As of September 30, 2023 and December 31, 2022, the Company accounted for the following investments in the investee’s common stock under the equity method, which are included in the investments in non-consolidated entities and non-marketable equity securities on the interim unaudited condensed consolidated balance sheets (amounts in thousands):


		As of September 30, 2023			As of December 31, 2022
	Formation	Common Stock	Carrying		Common Stock	Carrying
Investee	Date	Ownership %	Value		Ownership %	Value
HyVia	Q2 2021	50%	$	14,876	50%	$	11,281
AccionaPlug S.L.	Q4 2021	50%		3,821	50%		2,225
SK Plug Hyverse	Q1 2022	49%		42,559	49%		8,937
			$	61,256		$	22,443