The Company categorizes its assets and liabilities measured at fair value in accordance with the authoritative accounting guidance that establishes a consistent framework for measuring fair value and expands disclosures for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as the exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:

The following table identifies the Company’s assets that were measured at fair value on a recurring basis (in thousands):


June 30, 2023	Level		Amortized Cost		Gross unrealized gains		Gross unrealized losses			Estimated Fair Value
Cash and cash equivalents - Money market mutual funds		1	$	117,985	$	—	$	—		$	117,985
Short-term investments - U.S. Treasury securities		2		133,371		1		(181	)		133,191
Total			$	251,356	$	1	$	(181	)	$	251,176
December 31, 2022
Cash and cash equivalents - Money market mutual funds		1	$	209,273	$	—	$	—		$	209,273
Short-term investments - U.S. Treasury securities		2		63,456		407		—			63,863
Total			$	272,729	$	407	$	—		$	273,136

There were no transfers between the Level 1 and Level 2 categories or into or out of the Level 3 category during the periods presented. During the three and six months ended June 30, 2023, the Company purchased zero and $131.4 million, respectively, in short-term investments.

The Company’s short-term investments portfolio contains investments in U.S. Treasury securities that have an effective maturity date that is less than one year from the respective balance sheet date. The Company's cash and cash equivalents consists of money market mutual funds that have remaining maturities when purchased of 90 days or less.

The Company recorded $0.2 million and $0.6 million in net unrealized losses to accumulated other comprehensive (loss) gain, net in the three and six months ended June 30, 2023, respectively. Management determined that the gross unrealized losses on the Company’s available-for-sale securities as of June 30, 2023, were primarily attributable to current economic and market conditions and not credit risk. As of June 30, 2023 and December 31, 2022, no allowance for credit losses was recorded. It is neither management’s intention to sell nor is it more likely than not that the Company will be required to sell any investments prior to recovery of their amortized cost basis, which may be at maturity.

As of June 30, 2023 and December 31, 2022, the Company did not have any liabilities that were measured at fair value on a recurring basis.