Cash, cash equivalents and investments

As of June 30, 2019 and December 31, 2018, cash, cash equivalents and investments comprised of funds in depository, money market accounts, U.S. treasury securities, asset backed securities and corporate bonds. The following table presents the cash equivalents and investments carried at fair value in accordance with the hierarchy defined in Note 2 (in thousands):



	Total		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
June 30, 2019
Money market funds, included in cash equivalents	$	11,429	$	11,429	$	—	$	—
Corporate bonds, included in cash equivalents	2,598		—		2,598		—
Investments - U.S. treasuries	6,592		6,592		—		—
Investments - Asset-backed securities	10,041		—		10,041		—
Investments - Corporate bonds	28,149		—		28,149		—
Total	$	58,809	$	18,021	$	40,788	$	—

December 31, 2018
Money market funds, included in cash equivalents	$	7,791	$	7,791	$	—	$	—
Corporate bonds, included in cash equivalents	10,910		—		10,910		—
Investments - U.S. treasuries	7,518		7,518		—		—
Investments - Asset-backed securities	5,758		—		5,758		—
Investments - Corporate bonds	39,964		—		39,964		—
Total	$	71,941	$	15,309	$	56,632	$	—

Cash equivalents and marketable securities have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income and market-based approaches and observable market inputs to determine value. The Company validates the prices provided by its third-party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources, as needed. After completing its validation procedures, the Company did not adjust any fair value measurements provided by the pricing services as of June 30, 2019.

Investments at June 30, 2019 consist of the following (in thousands):



	Contractual maturity (in days)	Amortized Cost		Unrealized gains		Unrealized losses			Fair Value
Investments
U.S. treasuries	62-259	$	6,587	$	5	$	—		$	6,592
Asset-backed securities	15-233	10,050		5		(14		)	10,041
Corporate bonds	23-242	28,191		8		(50		)	28,149
Total		$	44,828	$	18	$	(64	)	$	44,782

The Company recorded realized gains of $0.1 million from the maturity of available-for-sale securities during the three and six months ended June 30, 2019, respectively. The Company recorded $0.1 million of realized gains and $0.1 million in realized losses during the three and six months ended June 30, 2018, respectively.