Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2015

Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes the assets measured at fair value on a recurring basis at March 31, 2015 (in thousands):


Description	March 31, 2015		Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	$	45,549	$	45,549	$	—	$	—

Total	$	45,549	$	45,549	$	—	$	—


Description	March 31, 2015		Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (Level 3)
Liabilities:
Warrant liability	$	1,915	$	—	$	—	$	1,915

Total	$	1,915	$	—	$	—	$	1,915

The following table summarizes the assets and liabilities measured at fair value on a recurring basis at December 31, 2014 (in thousands):


Description	December 31, 2014		Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	$	54,059	$	54,059	$	—	$	—

Total	$	54,059	$	54,059	$	—	$	—


Description	December 31, 2014		Active Markets (Level 1)		Observable Inputs (Level 2)		Unobservable Inputs (Level 3)
Liabilities:
Warrant liability	$	3,219	$	—	$	—	$	3,219

Total	$	3,219	$	—	$	—	$	3,219

Summary of Assumptions Used in Valuing Warrants

The Company measures the fair value of the warrants classified as a liability at each reporting date using the Black-Scholes option pricing model using the following assumptions:


	March 31, 2015			December 31, 2014
Risk-free interest rate		0.89	%		1.10	%
Expected dividend yield		0.00	%		0.00	%
Expected term (in years)		2.67			2.92
Expected volatility		62.19	%		56.79	%

Summary of Changes in the Fair Value of the Company's Preferred Stock Warrant Liability

The following table sets forth a summary of changes in the fair value of the Company’s preferred stock warrant liability, which represented a recurring measurement classified within Level 3 of the fair value hierarchy, wherein fair value was estimated using significant unobservable inputs (in thousands):


Beginning balance, January 1, 2015	$	3,219
Change in fair value		(1,304	)

Ending balance, March 31, 2015	$	1,915