8. Term Loan

In August 2014, the Company received a $7,500,000 secured term loan from a finance company. The loan is secured by a lien on all of the Company’s assets, excluding intellectual property, which was subject to a negative pledge. The loan contains certain additional nonfinancial covenants. In connection with the loan agreement, the Company’s cash and investment accounts are subject to account control agreements with the finance company that give the finance company the right to assume control of the accounts in the event of a loan default. Loan defaults are defined in the loan agreement and include, among others, the finance company’s determination that there is a material adverse change in the Company’s operations. Interest on the loan is at a rate of the greater of 7.95%, or 7.95% plus the prime rate as reported in The Wall Street Journal minus 3.25%. The interest rate effective from loan inception to December 16, 2015 was 7.95%. Effective December 17, 2015, the prime rate as reported by The Wall Street Journal increased 0.25% resulting in an increase to the current interest rate, which is now 8.20%. The loan was interest‑only for nine months, and is repayable in equal monthly payments of principal and interest of approximately $305,000 over 27 months, which began in June 2015. Debt consisted of the following as of December 31, 2015 and 2014:

Interest expense, which includes amortization of a discount and the accrual of a termination fee, was approximately $800,000 and $329,000 for the years ended December 31, 2015 and 2014, respectively, in the accompanying statements of operations. Future principal payments are as follows:

In connection with the term loan, the Company issued warrants to purchase 625,208 shares of Series B convertible preferred stock at an exercise price of $0.2999 per share that is exercisable for a period ending five years following the Company’s IPO, which is October 2020. Upon the closing of the Company’s IPO, these warrants became warrants to purchase 22,328 shares of common stock at an exercise price of $8.40 per share, in accordance with their terms. The Company’s warrants to purchase shares of Series B convertible preferred stock represented a freestanding financial instrument that was indexed to an obligation of the Company to repurchase its Series B convertible preferred stock by transferring assets and therefore met the criteria to be classified as a liability under ASC 480, Distinguishing Liabilities from Equity. The Company records the warrant liability at its fair value using the Black‑Scholes option pricing model and revalues the warrant at each reporting date (see Note 4).

Upon issuance of the term loan, the Company paid lender fees of $110,000 and is required to pay a one‑time fee at maturity of $187,500.  The lender fees and warrants were recorded as a discount to the carrying amounts of the current and long term portions of the term loan. Amortization of the debt discount was $159,210 and $68,861 during the years ended December 31, 2015 and 2014, respectively. Accretion of the one‑time fee was $84,144 and $36,394 during the years ended December 31, 2015 and 2014, respectively. The amortization of the debt discount and the accretion of the one-time fee are reflected as a components of interest expense within the Company’s statements of operations.