Warrants	3 Months Ended
Mar. 31, 2014
Warrants
Warrants	4. Warrants In connection with its various financing transactions, the Company issued warrants to purchase shares of preferred stock which had provisions where the underlying issuance was contingently redeemable based on events outside the Company’s control and were recorded as a liability in accordance with ASC 480-10. The warrants were classified as liabilities and were recorded on the Company’s balance sheet at fair value on the date of issuance and marked- to-market on each subsequent reporting period, with the fair value changes recognized in the statement of operations. Subsequent to the pricing of the IPO, the Company estimated the fair values of the warrants at each reporting period using a Black-Scholes option-pricing model, which is based, in part, upon subjective assumptions including but not limited to stock price volatility, the expected life of the warrants, the risk free interest rate and the fair value of the common stock underlying the warrants. The Company estimates the volatility of its stock based on public company peer group historical volatility that is in line with the expected remaining life of the warrants. The risk free interest rate is based on the U.S. Treasury zero-coupon bond for a maturity similar to the expected remaining life of the warrants. The expected remaining life of the warrants is assumed to be equivalent to their remaining contractual term. Prior to the pricing of the IPO, a Monte Carlo valuation model was utilized to estimate the fair value of the warrants based on the probability and timing of future financings. The assumptions used in calculating the estimated fair market value at each reporting period prior to the closing of the Company’s IPO represent the Company’s best estimate, however, do involve inherent uncertainties. The estimated fair value of the warrants was determined using the Monte Carlo valuation model which totaled $0.3 million and was comprised of $0.1 million and $0.2 million as of and for the September and November 2012 financing, respectively, and was recorded as a discount on the related convertible promissory notes and amortized as interest expense over the term of the convertible promissory notes. Inherent in the Monte Carlo valuation model are assumptions related to expected stock-price volatility, expected life and risk-free interest rate. The Company estimates the volatility of its stock based on public company peer group historical volatility that is in line with the expected remaining life of the warrants. The risk-free interest rate is based on the U.S. Treasury zero-coupon bond on the grant date for a maturity similar to the expected remaining life of the warrants. The expected life of the warrants is assumed to be equivalent to their remaining contractual term. The dividend rate is based on the historical rate, which the Company anticipates to remain at zero. The Monte Carlo model was used prior to the closing of the Company’s IPO to appropriately value the potential future exercise price based on various exit scenarios. This requires Level 3 inputs which are based on the Company’s estimates of the probability and timing of potential future financings. Upon the closing of the Company’s IPO, all warrants exercisable for 1,940,000 shares of Series A preferred stock, at an exercise price of $1.00 per share, were automatically converted into warrants exercisable for 277,690 shares of common stock, at an exercise price of $6.99 per share. As a result, the Company concluded the warrants outstanding no longer met the criteria to be classified as liabilities and were reclassified to additional paid-in capital at fair value on the date of reclassification. The 277,690 warrants outstanding as of March 31, 2014 expire in February 2018. During the three months ended March 31, 2014 and 2013, and the period from inception through March 31, 2014, the Company recognized a loss of $0, $42,000 and $2.6 million, respectively, relating to the change in the fair value of the warrant liability.

4. Warrants

In connection with its various financing transactions, the Company issued warrants to purchase shares of preferred stock which had provisions where the underlying issuance was contingently redeemable based on events outside the Company’s control and were recorded as a liability in accordance with ASC 480-10. The warrants were classified as liabilities and were recorded on the Company’s balance sheet at fair value on the date of issuance and marked- to-market on each subsequent reporting period, with the fair value changes recognized in the statement of operations. Subsequent to the pricing of the IPO, the Company estimated the fair values of the warrants at each reporting period using a Black-Scholes option-pricing model, which is based, in part, upon subjective assumptions including but not limited to stock price volatility, the expected life of the warrants, the risk free interest rate and the fair value of the common stock underlying the warrants. The Company estimates the volatility of its stock based on public company peer group historical volatility that is in line with the expected remaining life of the warrants. The risk free interest rate is based on the U.S. Treasury zero-coupon bond for a maturity similar to the expected remaining life of the warrants. The expected remaining life of the warrants is assumed to be equivalent to their remaining contractual term. Prior to the pricing of the IPO, a Monte Carlo valuation model was utilized to estimate the fair value of the warrants based on the probability and timing of future financings.

The assumptions used in calculating the estimated fair market value at each reporting period prior to the closing of the Company’s IPO represent the Company’s best estimate, however, do involve inherent uncertainties. The estimated fair value of the warrants was determined using the Monte Carlo valuation model which totaled $0.3 million and was comprised of $0.1 million and $0.2 million as of and for the September and November 2012 financing, respectively, and was recorded as a discount on the related convertible promissory notes and amortized as interest expense over the term of the convertible promissory notes. Inherent in the Monte Carlo valuation model are assumptions related to expected stock-price volatility, expected life and risk-free interest rate. The Company estimates the volatility of its stock based on public company peer group historical volatility that is in line with the expected remaining life of the warrants. The risk-free interest rate is based on the U.S. Treasury zero-coupon bond on the grant date for a maturity similar to the expected remaining life of the warrants. The expected life of the warrants is assumed to be equivalent to their remaining contractual term. The dividend rate is based on the historical rate, which the Company anticipates to remain at zero. The Monte Carlo model was used prior to the closing of the Company’s IPO to appropriately value the potential future exercise price based on various exit scenarios. This requires Level 3 inputs which are based on the Company’s estimates of the probability and timing of potential future financings.

Upon the closing of the Company’s IPO, all warrants exercisable for 1,940,000 shares of Series A preferred stock, at an exercise price of $1.00 per share, were automatically converted into warrants exercisable for 277,690 shares of common stock, at an exercise price of $6.99 per share. As a result, the Company concluded the warrants outstanding no longer met the criteria to be classified as liabilities and were reclassified to additional paid-in capital at fair value on the date of reclassification. The 277,690 warrants outstanding as of March 31, 2014 expire in February 2018. During the three months ended March 31, 2014 and 2013, and the period from inception through March 31, 2014, the Company recognized a loss of $0, $42,000 and $2.6 million, respectively, relating to the change in the fair value of the warrant liability.