The amortized costs, unrealized gains and losses and estimated fair values of our short-term investments were as follows (in thousands):


	October 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government securities	$	52,723	$	—	$	(698)	$	52,025
Corporate bonds	51,918		—		(459)		51,459
Commercial paper	100,908		—		—		100,908
Supranational bonds	9,998		—		(31)		9,967
Foreign government securities	4,033		—		(51)		3,982
Total short-term investments	$	219,580	$	—	$	(1,239)	$	218,341


	January 31, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
U.S. government securities	$	18,082	$	—	$	(155)	$	17,927
Corporate bonds	21,225		—		(49)		21,176
Commercial paper	55,234		—		—		55,234
Supranational bonds	3,503		—		—		3,503
Foreign government securities	4,064		—		(22)		4,042
Total short-term investments	$	102,108	$	—	$	(226)	$	101,882

There were no material realized gains or losses from sales of marketable securities that were reclassified out of accumulated other comprehensive loss into investment income during the three and nine months ended October 31, 2022 and 2021. We had no significant unrealized losses on our available-for-sale securities as of October 31, 2022 and January 31, 2022, and we do not expect material credit losses on our current investments in future periods. All securities had stated effective maturities of less than one year as of October 31, 2022.