Marketable Securities

3 Months Ended

Mar. 31, 2021

4. Marketable Securities

Marketable securities consist of the following:


	March 31, 2021
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(in thousands)	Cost		Gain		Loss		Fair Value
Corporate bonds	$	231,530	$	337	$	(158)	$	231,709
Total	$	231,530	$	337	$	(158)	$	231,709


	December 31, 2020
			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
(in thousands)	Cost		Gain		Loss		Fair Value
Corporate bonds	$	242,900	$	854	$	(75)	$	243,679
Commercial paper		6,997		—		—		6,997
Total	$	249,897	$	854	$	(75)	$	250,676

The Company uses the specific identification method when calculating realized gains and losses. For the three months ended March 31, 2021 and 2020, respectively, the Company recorded approximately $54,000 and $64,000 in realized gains on available-for-sale securities, which is included in other income, net on the condensed statements of operations.

The Company reviewed all of the investments which were in a loss position at the respective balance sheet dates, as well as the remainder of the portfolio. The Company has analyzed the unrealized losses and determined that market conditions were the primary factor driving these changes. After analyzing the securities in an unrealized loss position, the portion of these losses that relate to changes in credit quality is insignificant. The Company does not intend to sell these securities, nor is it more likely than not that the Company will be required to sell them prior to the end of their contractual terms. Furthermore, the Company does not believe that these securities expose the Company to undue market risk or counterparty credit risk.

The following table summarizes maturities of the Company’s investments available-for-sale as of March 31, 2021:


	March 31, 2021
			Fair
(in thousands)	Cost		Value
Maturities:
Within 1 year	$	115,920	$	116,233
Between 1 to 2 years		115,610		115,476
Total investments available for sale	$	231,530	$	231,709

The Company has classified all of its investments available-for-sale, including those with maturities beyond one year, as current assets on the accompanying condensed balance sheets based on the highly-liquid nature of these investment securities and because these investment securities are considered available for use in current operations.