NOTE 8 – STOCK WARRANTS

The following table summarizes information with respect to outstanding warrants to purchase common stock of the Company, all of which were vested and exercisable, at December 31, 2017: 

During the year ended December 31, 2017, 2,250 warrants with an exercise price of $6.30 were exercised. During the year ended December 31, 2017, 33,089 and 44,521 warrants with exercise prices of $250.00 and $120.00, respectively, expired.

In connection with the October 2016 financing, the Company issued to the underwriter warrants to purchase up to an aggregate of 47,361 shares of the Company's common stock. The warrants are exercisable at $6.90 per share, expire five years from the date of issuance and have a fair value of $2.65. The Company measures the fair value of the issued warrants based on a Binomial option pricing model using certain assumptions discussed in the following paragraph, and the closing market price of the Company’s common stock on the date of the fair value determination.

The assumptions used in the valuation of warrants issued to Dawson were as follows:

The risk-free interest rate is based on the yield of Daily U.S. Treasury Yield Curve Rates with terms equal to the life of the warrants as of the grant date. The expected stock price volatility is based on comparable companies’ historical stock price volatility since the Company does not have sufficient historical volatility data because its equity shares have been publicly traded for only a limited period of time.