9. Common Stock Warrants

As of June 30, 2016 and December 31, 2015, the following common stock warrants were outstanding (in thousands, except for per share amounts):

In February 2016, in conjunction with services to be provided by a third-party consultant, the Company issued a warrant to purchase up to an aggregate of 165,000 unregistered shares of XOMA’s common stock at an exercise price equal to $0.77 per share. These warrants were exercisable immediately and have a five-year term expiring in February 2021. The estimated fair value of the warrants in the amount of $0.1 million was calculated using the Black-Scholes Model and was classified in stockholders’ deficit on the condensed consolidated balance sheet.

The Company revalued the December 2014 warrants at June 30, 2016 using the Black-Scholes Model and recorded a $44,000 and $3.0 million decrease in the estimated fair value as a gain in the revaluation of contingent warrant liabilities line of the Company’s condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2016, respectively. The Company revalued the March 2012 warrants at June 30, 2016 using the Black-Scholes Model and recorded a $3.2 million and $7.2 million decrease in the estimated fair value as a gain in the revaluation of contingent warrant liabilities line of the Company’s condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2016, respectively. The decrease in these liabilities is primarily due to the decrease in the market price of XOMA’s common stock at June 30, 2016 as compared to December 31, 2015. 

As of June 30, 2016 and December 31, 2015, the December 2014 warrants had an estimated fair value of zero and $3.0 million, respectively. As of June 30, 2016 and December 31, 2015, the March 2012 warrants had an estimated fair value of $0.3 million and $7.5 million, respectively.