In February through April 2018, the Company issued 9.00% secured convertible promissory notes with a collective face value of $3,000,000 (the “Initial 2018 Notes”). The Initial 2018 Notes (i) accrued simple interest at the rate of 9.00% per annum, (ii) matured on the earlier of December 31, 2018 or the close of a $15,000,000 equity financing (“Qualifying Equity Financing”) by the Company, and (iii) all outstanding principal and accrued interest was automatically convertible into equity or equity-linked securities sold in a Qualifying Equity Financing based upon a conversion rate equal to (x) a 10% discount to the price per share of a Qualifying Equity Financing, with (y) a floor of $10.80 per share. In addition, the holders of the Initial 2018 Notes were collectively issued warrants to purchase approximately 55,559 shares of common stock, at an exercise price of $10.80 per share and a term of five years (the “Initial 2018 Warrants”).

In May through August 2018, the Company issued additional 9.00% secured convertible promissory notes with a collective face value of $10,000,000 (the “Additional 2018 Notes”). In May 2018, all of the Initial 2018 Notes and related accrued interest, totaling $3,056,000, were converted into the Additional 2018 Notes, resulting in an aggregate principal amount of $13,056,000 (hereinafter collectively, the “2018 Notes”). The holders of the converted Initial 2018 Notes retained their respective Initial 2018 Warrants.

The 2018 Notes (i) accrued simple interest at the rate of 9.00% per annum, (ii) matured on the earlier of the closing of an initial public offering of the Company’s common stock on a national securities exchange or April 30, 2019, and (iii) all outstanding principal and accrued interest was automatically convertible into shares of common stock upon the closing of an IPO at the lesser of (x) $10.80 per share or (y) a 15% discount to the price per share of the IPO. In addition, the holders of the 2018 Notes were collectively issued 1,396,420 warrants to purchase common stock equal to 100% of the aggregate principal amount of the 2018 Notes divided by $9.35 per share (the “2018 Warrants”). The 2018 Warrants are exercisable for a term of five years, commencing on the close of an IPO, at an exercise price of $9.35 and are callable at the election of the Company at any time following the closing of an IPO. The 2018 Notes were secured by a security interest in all of the assets, tangible and intangible, of the Company.

The proceeds from the sale of the 2018 Notes, the 2018 Warrants and the Initial 2018 Warrants, were allocated to the instruments based on the relative fair values of the convertible debt instrument without the warrants and of the warrants themselves at the time of issuance. The portion of the proceeds, totaling $5,933,000 allocated to the 2018 Warrants, was accounted for as a discount to the debt, with the offsetting credit to additional paid-in capital. The remainder of the proceeds were allocated to the convertible debt instrument portion of the transaction. The resulting debt discount is amortized over the period from issuance to April 30, 2019, the stated maturity date of the debt.

Debt issuance costs were comprised of $389,000 of cash commissions and warrants with a fair value of $223,000, paid and issued, respectively, to third-parties in connection with the debt financing, and are reflected as a discount to the debt instrument, net of accumulated amortization, in the December 31, 2018 balance sheet. Debt issuance costs are amortized over the term of the debt as interest expense in the statement of operations.

Concurrent with the closing of the IPO on February 27, 2019, all outstanding principal and accrued interest outstanding under the 2018 Notes totaling $13,793,000 was automatically converted into 1,475,164 shares of the Company’s common stock at a conversion price per share of $9.35. As a result of the automatic conversion of the 2018 Notes and the application of conversion accounting, the Company recorded an immediate charge to interest expense of $1,384,000 for the year ended December 31, 2019, representing the write-off of the unamortized balance of debt discounts associated with the 2018 Warrants and cash commissions and warrants issued to third parties. Unamortized debt discounts at December 31, 2019 and 2018 totaled $0 and $2,684,000, respectively.

The non-detachable conversion feature embedded in the 2018 Notes provides for a conversion rate that is below market value at the commitment date, and therefore, represents a beneficial conversion feature (“BCF”). The BCF is generally recognized separately at issuance by allocating a portion of the debt proceeds equal to the intrinsic value of the BCF to additional paid-in capital. The resulting convertible debt discount is recognized as interest expense using the effective yield method. The BCF is measured using the commitment date stock price. However, the conversion feature associated with the 2018 Notes was not exercisable until the consummation of an initial public offering by the Company of its common stock, and therefore, was not required to be recognized in earnings until the IPO related contingency was resolved, which occurred on the IPO Closing Date. The commitment date is the IPO Closing Date and the commitment date stock price was $11.00 per share. The intrinsic value of the BCF on the IPO Closing Date, which was limited to the net proceeds allocated to the debt on a relative fair value basis, was approximately $7,067,000, and is reflected as additional interest expense in the statement of operations for the year ended December 31, 2019.

The weighted-average grant date fair value of 2018 Warrants issued during the year ended December 31, 2018 was $7.98. The aggregate fair value of 2018 Warrants that vested during the year ended December 31, 2018 was $10,296,926. The weighted-average exercise price and weighted-average remaining contractual term for the 2018 Warrants was $9.41 and 4.5 years. At December 31, 2019 the aggregate intrinsic value of the 2018 Warrants totaled $(10,230,000). 

The fair value of Debt Warrants issued was estimated on their respective issue dates using the Black Scholes-Merton option pricing model and the following weighted-average assumptions: