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

6 Months Ended

Jun. 30, 2022

Investments, All Other Investments [Abstract]

Schedule of Fair Value Hierarchy Assets and Liabilities

The valuation inputs hierarchy classification for assets measured at fair value on a recurring basis are summarized below as of June 30, 2022 and December 31, 2021 (in thousands). These tables do not include cash held in our money market savings accounts.

As of June 30, 2022		Level 1		Level 2		Level 3		Total
Assets
Corporate debt securities	$	-	$	29,006	$	-	$	29,006
U.S. Treasury securities		-		26,920		-		26,920
	$	-	$	55,926	$	-	$	55,926

As of December 31, 2021		Level 1		Level 2		Level 3		Total
Assets
Corporate debt securities	$	-	$	32,720	$	-	$	32,720
	$	-	$	32,720	$	-	$	32,720

Schedule of Unrealized Gain or Loss on Short-term Investments

Our short-term investments are summarized below as of June 30, 2022 and December 31, 2021 (in thousands).

								Investment
		Cost/		Gross		Gross		Securities,
		Amortized		Unrealized		Unrealized		Available-
		Cost		Gains		Losses		For-Sale
As of June 30, 2022
Assets
Corporate debt securities	$	29,118	$	3	$	(115)	$	29,006
U.S. Treasury securities		26,986		-		(66)		26,920
	$	56,104	$	3	$	(181)	$	55,926

								Investment
		Cost/		Gross		Gross		Securities,
		Amortized		Unrealized		Unrealized		Available-
		Cost		Gains		Losses		For-Sale
As of December 31, 2021
Assets
Corporate debt securities	$	32,739	$	3	$	(22)	$	32,720
	$	32,739	$	3	$	(22)	$	32,720

+Maturity Date of Available-for-sale Securities

The maturities of the investment securities available-for-sale as of June 30, 2022 and December 31, 2021 are shown below (in thousands):

				Gross		Gross
As of June 30, 2022		Amortized		Unrealized		Unrealized		Estimated
Maturity date		Cost		Gains		Losses		Fair Value
Less than one year	$	56,104	$	3	$	(181)	$	55,926
	$	56,104					$	55,926

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

Schedule of Unrealized Loss on Investment Securities

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 June 30, 2022 and December 31, 2021 (in thousands):

		Less than Twelve Months				Twelve Months or Greater				Total
As of June 30, 2022				Gross				Gross				Gross
		Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
		Value		Losses		Value		Losses		Value		Losses
Corporate debt securities	$	26,004	$	(115)	$	-	$	-	$	26,004	$	(115)
U.S. Treasury securities		26,920		(66)		-		-		26,920		(66)
	$	52,924	$	(181)	$	-	$	-	$	52,924	$	(181)

		Less than Twelve Months				Twelve Months or Greater				Total
As of December 31, 2021				Gross				Gross				Gross
		Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
		Value		Losses		Value		Losses		Value		Losses
Corporate debt securities	$	27,195	$	(22)	$	-	$	-	$	27,195	$	(22)
	$	27,195	$	(22)	$	-	$	-	$	27,195	$	(22)