4. Short-Term Investments

The following table summarizes the short-term investments held at March 31, 2020 and December 31, 2019 (in thousands):


			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
March 31, 2020
Corporate debt securities		7,774		—		(15)		7,759
Reverse repurchase agreements		34,000		—		—		34,000
Total	$	41,774	$	—	$	(15)	$	41,759


			Gross Unrealized		Gross Unrealized
	Amortized Cost		Gains		Losses		Fair Value
December 31, 2019
Commercial paper	$	1,993	$	—	$	—	$	1,993
Corporate debt securities		3,352		—		—		3,352
Reverse repurchase agreements		21,000		—		—		21,000
Total	$	26,345	$	—	$	—	$	26,345

The contractual maturities of all short-term investments held at March 31, 2020 and December 31, 2019 were one year or less. There were five short-term investments in an unrealized loss position at March 31, 2020, none of which had been in an unrealized loss position for more than 12 months. The aggregate fair value of these investments was approximately $7.8 million. There were four short-term investments in an unrealized loss position at December 31, 2019, none of which had been in an unrealized loss position for more than 12 months. The aggregate fair value of these investments was approximately $3.4 million. The Company did not hold any investments with other-than-temporary impairments at March 31, 2020 and December 31, 2019.

Gross realized gains and losses on the sales of short-term investments are included in other income, net. Unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income, as well as gains and losses reclassified out of accumulated other comprehensive income into other income, net were not material to the Company’s condensed consolidated results of operations. The cost of investments sold or the amount reclassified out of the accumulated other comprehensive income into other income, net is based on the specific identification method for purposes of recording realized gains and losses. All proceeds in the three-month periods ended March 31, 2020 and 2019 related to maturities of underlying investments. The gains on proceeds from maturities of short-term investments were not material to the Company’s condensed consolidated results of operations for the three months ended March 31, 2020 and 2019.