Cash and Investments in Marketable Securities

3 Months Ended

Mar. 31, 2021

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, 2021		December 31, 2020
Cash and cash equivalents	$	150,164	$	198,955
Short-term investments	887,152		862,941
Long-term investments	96,093		136,662
Total cash and investments in marketable securities	$	1,133,409	$	1,198,558

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, 2021 and December 31, 2020, 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):


	March 31, 2021								December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Fair Value
Corporate notes and bonds	$	510,521	$	313	$	(171)	$	510,663	$	687,469
Corporate commercial paper	478,448		35		(41)		478,442		313,497
Obligations of U.S. government agencies	4,880		4		—		4,884		2,382
Available-for-sale investments	$	993,849	$	352	$	(212)	$	993,989	$	1,003,348
Money market funds							123,607		179,302
Certificates of deposit							8,254		9,623
Cash							7,559		6,285
Total cash and investments in marketable securities							$	1,133,409	$	1,198,558

At December 31, 2020, our gross unrealized gains and losses totaled $1.1 million and $0.2 million, respectively.