Fair Value Measurements

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The Company measures and reports its cash equivalents, restricted cash, short-term investments and preferred stock warrant liabilities at fair value. The following table sets forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis by level within the fair value hierarchy:

	June 30, 2015
	Level 1		Level 2		Level 3		Total
	(in thousands)
Financial Assets
Money market funds	$	15,213	$	—	$	—	$	15,213
Restricted money market funds		225		—		—		225
Short-term investments		—		10,028		—		10,028
Total financial assets	$	15,438	$	10,028	$	—	$	25,466
Financial Liabilities
Preferred stock warrant liabilities	$	—	$	—	$	10,641	$	10,641

	December 31, 2014
	Level 1		Level 2		Level 3		Total
	(in thousands)
Financial Assets
Money market funds	$	27,847	$	—	$	—	$	27,847
Restricted money market funds		75		—		—		75
Short-term investments		—		10,010		—		10,010
Total financial assets	$	27,922	$	10,010	$	—	$	37,932
Financial Liabilities
Preferred stock warrant liabilities	$	—	$	—	$	1,810	$	1,810

Money market funds are measured at fair value on a recurring basis using quoted prices and are classified as a Level 1 input.

The short-term investments contain observable inputs. Accordingly, the carrying value of this instrument approximates its fair value and is classified as Level 2 inputs.

The Company’s preferred stock warrant liabilities contain unobservable inputs that reflect the Company’s own assumptions in which there is little, if any, market activity for at the measurement date. Accordingly, the Company’s warrant liabilities are measured at fair value on a recurring basis using unobservable inputs and are classified as Level 3 inputs. Refer to Note 9 for the valuation technique and assumptions used in estimating the fair value of the warrants.

There were no transfers between Levels 1, 2 or 3 for any of the periods presented. For the three and six months ended June 30, 2015, the Company realized a $0 and $10,000 other-than-temporary impairment loss on its short-term investments through other income (expense) in the accompanying condensed consolidated statements of operations.

The Company’s Level 3 liabilities consist of a preferred stock warrant liability (see Note 9). The following table provides a roll-forward of the Company’s warrant liabilities measured at fair value on a recurring basis using unobservable inputs (in thousands):

Balance as of December 31, 2014	$	1,810
Fair value of preferred stock warrants exercised		(1,125	)
Change in fair value of preferred stock warrants		9,956
Balance as of June 30, 2015	$	10,641

The preferred stock warrant liabilities will increase or decrease each period based on fluctuations of the fair value of the underlying preferred stock. The change in the fair value of preferred stock warrants for each period is recognized as a gain or loss in the condensed consolidated statements of operations.