STOCK-BASED COMPENSATION

Under our stock option plans, our board of directors may grant options to purchase common shares to our key employees, officers, directors and consultants. We account for stock options in accordance with FASB ASC Topic 718, Compensation - Stock Compensation, with option expense amortized over the vesting period based on the trinomial lattice option-pricing model fair value on the grant date, which includes a number of estimates that affect the amount of our expense. We expensed approximately $1,195,000 in stock-based compensation during the three months ended March 31, 2019, as compared with $372,000 for the three months ended March 31, 2018.

The status of our stock options and stock awards are summarized as follows:



	Number of options - as Restated		Weighted average exercise price - as Restated
Outstanding at December 31, 2018	3,254,799		$	3.18
Granted	1,277,500		7.73
Exercised	(270,549	)	2.87
Canceled and forfeited	(10,500	)	2.10
Outstanding at March 31, 2019	4,251,250		$	4.57

Common shares required to be issued upon the exercise of stock options would be issued from our authorized and unissued shares. We calculated the fair value of issued options utilizing a trinomial lattice with an expected life calculated via the simplified method as we do not have sufficient history to determine actual expected life.



	2019 Grants
Option value	$	7.15	-	$	7.91
Risk-free rate	2.6%		-	2.6		%
Expected dividend yield	—
Expected volatility	69.1%		-	69.1		%
Expected term (in years)	6