Fair Value Measurements

3 Months Ended

Mar. 31, 2021

4. Fair Value Measurements

As of March 31, 2021 and December 31, 2020, we had cash equivalents and short-term investments measured at fair value on a recurring basis.

Available-for-sale marketable securities consist of U.S. Treasury securities, which are measured at fair value using Level 1 inputs, and commercial paper and corporate debt securities which are measured at fair value using Level 2 inputs. We determine the fair value of Level 2 related securities with the aid of valuations provided by third parties using proprietary valuation models and analytical tools. These valuation models and analytical tools use market pricing or prices for similar instruments that are both objective and publicly available, including matrix pricing or reported trades, benchmark yields, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids and/or offers. We validate the fair values of Level 2 financial instruments by comparing these fair values to a third-party pricing source.

The following tables summarize, by major security type, our cash equivalents and short-term investments that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy, in thousands:

	March 31, 2021
	Total		Level 1		Level 2
Cash equivalents:
Money market funds	$	105,195	$	105,195	$	—

Short-term investments:
Commercial paper		169,353	—			169,353
Corporate debt securities		163,032	—			163,032
U.S. Treasury securities		160,653		160,653		—
Total short-term investments		493,038		160,653		332,385
Total	$	598,233	$	265,848	$	332,385

	December 31, 2020
	Total		Level 1		Level 2
Cash equivalents:
Money market funds	$	311,239	$	311,239	$	—
Commercial paper		5,998		—		5,998
Total cash equivalents		317,237		311,239		5,998

Short-term investments:
Commercial paper		106,350		—		106,350
Corporate debt securities		113,020		—		113,020
U.S. Treasury securities		88,457		88,457		—
Total short-term investments		307,827		88,457		219,370
Total	$	625,064	$	399,696	$	225,368

We believe that our term loan facility bears interest at a rate that approximates prevailing market rates for instruments with similar characteristics and, accordingly, the carrying value of the term loan facility approximates fair value. The fair value of our term loan facility is determined using Level 2 inputs in the fair value hierarchy.