NOTE 5. INVESTMENTS

The following tables summarize the Company’s available-for-sale investments at March 31, 2019 and December 31, 2018 (in thousands):



	March 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Certificates of deposit	$	8,817	$	9	$	(17	)	$	8,809
U.S. Treasury securities	25,401		8		(22		)	25,387
U.S. Agency securities	6,521		—		(20		)	6,501
Commercial paper	8,463		—		—			8,463
Asset-backed securities	4,390		1		—			4,391
Corporate notes and bonds	22,008		4		(13		)	21,999
Total	$	75,600	$	22	$	(72	)	$	75,550



	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Certificates of deposit	$	10,787	$	—	$	—		$	10,787
U.S. Treasury securities	22,185		1		(66		)	22,120
U.S. Agency securities	8,024		1		(45		)	7,980
Commercial paper	17,025		—		—			17,025
Asset-backed securities	12,007		—		(9		)	11,998
Corporate notes and bonds	30,361		—		(53		)	30,308
Total	$	100,389	$	2	$	(173	)	$	100,218

The following table summarizes the maturities of the Company’s available-for-sale securities at March 31, 2019 and December 31, 2018 (in thousands):



	March 31, 2019				December 31, 2018
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due in less than 1 year	$	68,462	$	68,394	$	83,030	$	82,893
Due in 1-3 years	7,138		7,156		17,359		17,325
Total	$	75,600	$	75,550	$	100,389	$	100,218

Proceeds from sales of marketable securities (including principal paydowns) for the three months ended March 31, 2019 and 2018 were $9.0 million and $3.0 million, respectively. The Company determines gains and losses of marketable securities based on specific identification of the securities sold. There were no material realized gains from sales of marketable securities for the three months ended March 31, 2019 and 2018. No material balances were reclassified out of accumulated other comprehensive income (loss) for the three months ended March 31, 2019 and 2018.

The Company monitors investments for other-than-temporary impairment. It was determined that unrealized gains and losses as of March 31, 2019 and December 31, 2018 are temporary in nature because the change in market value for those securities has resulted from fluctuating interest rates rather than a deterioration of the credit worthiness of the issuers. The Company does not intend to sell investments and it is more likely than not that we will not be required to sell investments before recovering the amortized cost.