4. INVESTMENT SECURITIES, AVAILABLE-FOR-SALE AND FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2022

Investments, All Other Investments [Abstract]

4. INVESTMENT SECURITIES, AVAILABLE-FOR-SALE AND FAIR VALUE MEASUREMENTS

4. INVESTMENT SECURITIES, AVAILABLE-FOR-SALE AND FAIR VALUE MEASUREMENTS

Our investment securities, available-for-sale are comprised of corporate debt securities. The principal markets for the debt securities are dealer markets which have a high level of price transparency. The market participants for debt securities are typically large money center banks and regional banks, brokers, dealers, pension funds, and other entities with debt investment portfolios.

Fair value is defined as the exchange price that would be received for 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 authoritative guidance establishes a three level fair value inputs hierarchy and requires an entity to maximize the use of observable valuation inputs and minimize the use of unobservable inputs. We use market data, assumptions and risks we believe market participants would use in measuring the fair value of the asset or liability, including the risks inherent in the inputs and the valuation techniques. The hierarchy is summarized below.

Level 1 – Quoted prices in active markets for identical assets and liabilities at the measurement date that the reporting entity has the ability to access.

Level 2 – Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.

Level 3 – Unobservable inputs for which there is little or no market data, which requires us to develop our own assumptions, which are significant to the measurement of the fair values.

The valuation inputs hierarchy classification for assets measured at fair value on a recurring basis are summarized below as of December 31, 2022 and 2021 (in thousands). These tables do not include cash held in our money market savings accounts.

As of December 31, 2022	Level 1		Level 2		Level 3		Total
Assets
Corporate debt securities	$	—	$	15,500	$	—	$	15,500
U.S. Treasury securities		—		46,673		—		46,673
	$	—	$	62,173	$	—	$	62,173
As of December 31, 2021	Level 1		Level 2		Level 3		Total
Assets
Corporate debt securities	$	—	$	32,720	$	—	$	32,720
	$	—	$	32,720	$	—	$	32,720

Our short-term investments are summarized below as of December 31, 2022 and 2021 (in thousands).

								Investment
	Cost/		Gross		Gross			Securities,
	Amortized		Unrealized		Unrealized			Available-
	Cost		Gains		Losses			For-Sale
As of December 31, 2022
Assets
Corporate debt securities	$	15,538	$	—	$	(38	)	$	15,500
U.S. Treasury securities		46,762		2		(91	)		46,673
	$	62,300	$	2	$	(129	)	$	62,173
As of December 31, 2021
Assets
Corporate debt securities	$	32,739	$	3	$	(22	)	$	32,720
	$	32,739	$	3	$	(22	)	$	32,720

The maturities of the investment securities available-for-sale as of December 31, 2022 and 2021 are shown below (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
As of December 31, 2022
Maturity date
Less than one year	$	62,300	$	2	$	(129	)	$	62,173
	$	62,300						$	62,173
As of December 31, 2021
Less than one year	$	32,739	$	3	$	(22	)	$	32,720
	$	32,739						$	32,720

The following table summarizes investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for more than 12 months as of December 31, 2022 and 2021 (in thousands):

	Less than Twelve Months					Twelve Months or Greater				Total
			Gross					Gross				Gross
	Fair		Unrealized			Fair		Unrealized		Fair		Unrealized
	Value		Losses			Value		Losses		Value		Losses
As of December 31, 2022
Corporate debt securities	$	12,295	$	(38	)	$	—	$	—		12,295		(38	)
U.S. Treasury securities		34,530		(91	)		—		—		34,530		(91	)
	$	46,825	$	(129	)	$	—	$	—	$	46,825	$	(129	)
As of December 31, 2021
Corporate debt securities	$	27,195	$	(22	)	$	—	$	—		27,195		(22	)
	$	27,195	$	(22	)	$	—	$	—	$	27,195	$	(22	)