5. Derivative Liabilities

The Company’s derivative instruments on January 1, 2018 included options to purchase 19,441 common shares, the exercise prices for which are denominated in a currency other than the Company’s functional currency, as follows:

Contractor options to purchase 17,394 common shares exercisable at CAD$1.62 per whole common share that expire on April 4, 2018;

Contractor options to purchase 2,047 common shares exercisable at CAD$2.43 per whole common share that expire on May 18, 2018.

During the year ended December 31, 2018, all of these derivative options were exercised. This resulted in gross proceeds of $26,109, the issuance of 19,441 common shares and a non-cash, realized gain on the extinguishment of the remaining derivative liability of $167,131.

During the fiscal years ended December 31, 2011 and 2010, the Company issued 35,892 and 28,796, respectively, options to contractors with a Canadian dollar denominated strike price. Consequently, the Company had derivatives relating to these options since the strike price is denominated in a currency other than the US dollar functional currency of the Company. While there is an exception to this rule for employees in ASU 2010‑13 “Compensation-Stock Compensation (Topic 718): Effect of Denominating the exercise price of a share-based payment award in the currency of the market in which the underlying equity security trades”, no such exception exists for contractors. These options were marked to market until the earlier of their expiry or exercise. All Canadian denominated options issued to contractors fully vested at issuance and were to expire seven years from date of issuance. The fair value of these options at December 31, 2019 and December 31, 2018 was $0. The unrealized gain for these options for the year ended December 31, 2018 was $167,131.

The following is a summary of Canadian denominated contractor option activity for the year ended December 31, 2018 and 2019.


	Number of Options
	Outstanding and	Weighted
	Exercisable	Average Exercise
Share Prices Reported in $CAD	(in thousands)	Price
Outstanding and exercisable at December 31, 2017	19	$	1.71
Exercised	(19)	$	1.71
Outstanding and exercisable at December 31, 2018	—		—
Outstanding and exercisable at December 31, 2019	—		—

The following table presents gain on change in derivative valuation for the year ended December 31, 2019 and December 31, 2018:


	Gain (in thousands) on
	Derivative Instruments at
	December 31,
Derivative Warrants/Options	2019	2018
Options (various expiration dates)	—	167
Total	—	167