Marketable Securities

9 Months Ended

Sep. 30, 2020

Marketable Securities

Marketable Securities

4. Marketable Securities

Marketable securities consist of the following:

	September 30, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(in thousands)	Cost		Gain		Loss		Fair Value
Agency bonds (government sponsored enterprises)	$	7,342	$	23	$	—	$	7,365
Corporate bonds		253,052		1,330		(55)		254,327
Commercial paper		6,980		—		—		6,980
Total	$	267,374	$	1,353	$	(55)	$	268,672

	December 31, 2019
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(in thousands)	Cost		Gain		Loss		Fair Value
U.S. treasury securities	$	4,991	$	—	$	—	$	4,991
Agency bonds (government sponsored enterprises)		24,437		15		(1)		24,451
Corporate bonds		271,124		103		(155)		271,072
Total	$	300,552	$	118	$	(156)	$	300,514

As of September 30, 2020, no marketable securities are considered to be other-than-temporarily impaired. The Company uses the specific identification method when calculating realized gains and losses. For the three and nine months ended September 30, 2020, respectively, the Company recorded approximately $3,000 and $70,000 in realized gains on available-for-sale securities, which is included in other income, net on the condensed statements of operations.