4.	Common Stock Warrants

The following table summarizes the common stock warrant activity from December 31, 2013 through September 30, 2014:


	Shares			Weighted Average Exercise Price
Outstanding, December 31, 2013		6,035,229		$	3.63
Granted		—			—
Exercised		576,734			3.11
Forfeited/cancelled		(7,500	)		15.00

Outstanding, September 30, 2014		5,450,995		$	3.66

Consultant Warrants

In January 2013, the Company entered into an agreement with a consultant that provided for the grant of warrants for the purchase of 5,000 shares of common stock at an exercise price of $2.65 per share. The following assumptions were used to value the warrants: an expected life of 3 years, volatility of 87%, risk free interest rate of 0.42% and zero dividends. The Company recognized an expense of $7,000 related to these warrants at the time of grant as they were vested upon issuance.

Warrants Modification

On May 6, 2013, the Company modified the terms of the Class A-2 and Class B warrants that were originally issued to the 10X Fund with the Series B Preferred Stock offering. The Class B warrants were modified to allow for the cashless exercise of all 4,000,000 outstanding Class B warrants. Previously, only half of the Class B warrants allowed for cashless exercise. The Class A-2 warrants for the purchase of 1,000,000 shares of common and all of the Class B warrants had their exercisable life extended by an additional five years. In exchange for these modifications, the 10X Fund agreed to a future amendment of the Company’s Series B certificate of designation to remove the redemption provision such that the Series B Preferred Stock will no longer be redeemable, if and when the Company will no longer be required to issue Dr. Platt a promissory note as may currently be required under the separation agreement (see Note 8). Should the Company amend their Series B certificate of designation in the future as described above, the Company will be required at that time to evaluate whether such amendment is to be accounted for as a modification or an extinguishment of the Company’s Series B Preferred Stock. The Company has accounted for the modified terms of the Class A-2 and Class B warrants pursuant to ASC 718, Stock Compensation, whereby the Company has recognized a charge for the change in fair value of the warrants immediately before and immediately after the modification. The Company recognized a charge of $8,763,000 related to the extension of the 5,000,000 warrants in the quarter ended June 30, 2013. The following assumptions were used to value the extension of the warrants immediately before and immediately after the modification: a) immediately before the modification—an expected life range of 0.77 to 2.01 years, volatility range of 77% to 96%, risk free interest rate range of 0.11% to 0.22% and zero dividends and; b) immediately following the modification—an expected life range of 5.78 to 7.02 years, volatility range of 113% to 122%, risk free interest rate range of 0.74% to 1.19% and zero dividends.