Fair Value Measurments (Tables)

9 Months Ended

Sep. 30, 2016

Fair Value Measurements.

Assumptions used to calculate common stock warrants

	September 30, 2016					September 30, 2015
Risk-free interest rate	0.68	%	-	0.77	%	0.37	%	-	1.010	%
Volatility	59.60	%	-	60.60	%	55.93	%	-	123.53	%
Expected average term	1.39		-	2.29		0.67		-	3.30

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation

The following table shows reconciliations of the beginning and ending balances for the common stock warrant liability (in thousands):

	Nine months ended
Common stock warrant liability	September 30, 2016		September 30, 2015
Beginning of period	$	5,735	$	9,418
Change in fair value of common stock warrants		(4,709)		(4,603)
Exercise of common stock warrants		(141)		(22)
End of period	$	885	$	4,793