Our financial instruments measured at fair value on a recurring basis are cash equivalents and short-term investments.

Our fixed income available-for-sale securities consist of high quality, investment grade securities. We value these securities based on pricing from pricing vendors, who may use quoted prices in active markets for identical assets (Level 1) or inputs other than quoted prices that are observable either directly or indirectly (Level 2) in determining fair value.

Financial instruments are valued based on quoted market prices in active markets include mostly money market securities. Such instruments are generally classified within Level 1 of the fair value hierarchy.

Instruments valued based on quoted prices in markets that are less active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency are generally classified within Level 2 of the fair value hierarchy and include U.S. treasury securities.

Instruments valued based on unobservable inputs which reflect the reporting entity’s own assumptions or data that market participants would use in valuing an instrument are generally classified within Level 3 of the fair value hierarchy. As of June 30, 2020 and December 31, 2019, we did not hold any Level 3 instruments.

Financial instruments measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 are classified based on the valuation technique in the table below (in thousands):



	June 30, 2020
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market accounts	$	45,605	$	—	$	—	$	45,605
Total assets at fair value (1)	$	45,605	$	—	$	—	$	45,605



	December 31, 2019
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Money market accounts	$	63,351	$	—	$	—	$	63,351
U.S. Treasury securities	—		3,019		—		3,019
Total assets at fair value (2)	$	63,351	$	3,019	$	—	$	66,370

The contractual maturities of our available-for-sale securities on June 30, 2020 and December 31, 2019 were all due within one year. There were no transfers of instruments between Level 1 and 2 during the three and six months ended June 30, 2020 and the year ended December 31, 2019.

Money market accounts are classified as cash equivalents and U.S. Treasury securities (classified as available-for-sale securities), with maturity dates less than one year, are within short-term investments on our Condensed Consolidated Balance Sheets.

Short-term investments as of December 31, 2019 consisted of the following (in thousands):



	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
U.S. Treasury securities	$	3,018	$	1	$	—	$	3,019
Total	$	3,018	$	1	$	—	$	3,019