Cash and Investments in Marketable Securities

3 Months Ended

Mar. 31, 2022

Cash and Investments in Marketable Securities

Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):


	Estimated Fair Value at
	March 31, 2022		December 31, 2021
Cash and cash equivalents	$	67,993	$	25,218
Short-term investments	599,032		708,737
Long-term investments	37,363		64,828
Total cash and investments in marketable securities	$	704,388	$	798,783

We invest in liquid, high quality debt securities. Our investments in debt securities are subject to interest rate risk. To minimize the exposure due to an adverse shift in interest rates, we invest in securities with maturities of two years or less and maintain a weighted average maturity of one year or less. As of March 31, 2022 and December 31, 2021, all of our long-term investments had maturities between one and two years.

Our portfolio of cash and investments in marketable securities includes (in thousands):


	Fair Value Hierarchy Level	March 31, 2022								December 31, 2021
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Fair Value
Corporate notes and bonds	2	$	196,643	$	4	$	(1,270)	$	195,377	$	278,121
Corporate commercial paper	2	439,280		—		(1,479)		437,801		478,629
Obligations of U.S. government agencies	2	4,880		—		(9)		4,871		5,875
Available-for-sale investments		$	640,803	$	4	$	(2,758)	$	638,049	$	762,625
Money market funds	1							43,523		23,968
Certificates of deposit	2							10,894		10,940
Cash	N/A							11,922		1,250
Total cash and investments in marketable securities								$	704,388	$	798,783

For the three months ended March 31, 2022 and 2021, there were no transfers between Level 1 and Level 2 of the fair value hierarchy. At December 31, 2021, our gross unrealized losses totaled $0.7 million, and our gross unrealized gains were insignificant.