5.	Warrant Liability

Warrants with exercise price reset features (down-round protection) were accounted for as liabilities, with changes in the fair value included in net loss for the respective periods. The fair value of the liability associated with the warrants with this reset feature was $0 as of September 30, 2013, and $0 and $418,000 in gains from the change in fair value of warrants were recorded for the three and nine months ended September 30, 2013, respectively. We recorded $863,000 and $1,244,000 in losses for the three and nine months ended September 30, 2012, respectively.

All changes in the fair value of the warrants were to be recognized in earnings until such time as the warrants were exercised or they expire. These warrants expired as of August 2013. The warrants were not traded in an active securities market, and as such, we estimated the fair value of these warrants using an option pricing model with the following assumptions:

	As of September 30, 2013		As of December 31, 2012
Expected term		—	0.61 years
Common stock market price	$	—	$	2.80
Risk-free interest rate		—		0.11	%
Expected volatility		—		73.88	%
Resulting fair value (per warrant)	$	—	$	0.20

Expected volatility was based primarily on historical volatility. Historical volatility was computed using daily pricing observations for recent periods that corresponded to the expected term of the warrants. We believe this method produced an estimate that was representative of our expectations of future volatility over the expected term of these warrants. The expected life was based on the remaining contractual term of the warrants. The risk-free interest rate was the interest rate for treasury constant maturity instruments published by the Federal Reserve Board that was closest to the expected term of the warrants. The fair value of these warrants also incorporated our assumptions about future equity issuances and their impact to the down-round protection feature.

Fluctuations in the fair value of the warrants were impacted by unobservable inputs, most significantly the assumption with regards to future equity issuances and its impact to the down-round protection feature. Significant increases (decreases) in this input in isolation would have resulted in a significantly higher (lower) fair value measurement.