15. Warrants

The exercise price of the warrants and the number of warrant shares exercisable have been retroactively restated to reflect the 2-for-1 forward stock split effected on December 20, 2017.

In February 2016, pursuant to a securities purchase agreement, the Company issued warrants to purchase up to 260,870 shares of the Company’s common stock at an exercise price of $0.575 per share in connection with the February 2016 convertible promissory note which may be exercised by the warrant holders between August 28, 2016 and February 28, 2019. In April 2016, the Company issued warrants to the same holders to purchase up to 65,218 shares of the Company’s common stock at an exercise price of $0.575 per share in connection with the April 4, 2016 convertible promissory note which may be exercised by the warrant holder until April 4, 2019 (See Note 12).

On May 18, 2018, the warrant holder exercised warrants to purchase 201,088 shares of the Company’s common stock on a cashless basis.

On April 4, 2016, the Company issued warrants to purchase up to 124,440 shares of the Company’s common stock at an exercise price of $0.575 per share which may be exercised by the warrant holders until April 4, 2019. The warrants were issued to placement agents in relation to securing the February 29, 2016 and April 4, 2016 convertible promissory notes (See Note 12).

In connection with the private placement agreements entered into with accredited investors between February 26, 2018 and May 31, 2018, for each USD $1,000 debenture unit the Company issued two-year warrants to purchase up to 1082.25 shares of the Company’s common stock and for each CDN $1,000 debenture unit the Company issued two-year warrants to purchase up to 832.50 shares of the Company’s common stock at an exercise price of $0.50 per share. (See Note 12)

The fair value of the warrants was calculated using the Black-Scholes model on the date of issuance and was recorded as debt discount, which has been amortized as interest expense over the life of the debt.

The following assumptions were used to calculate the fair value at issuance for the warrants outstanding at December 31, 2018:

A summary of warrant transactions during the year ended December 31, 2018 is as follows: