6. Common Shares

Warrants

Outstanding warrants are summarized in the following table:


		Weighted		Weighted
		average		average
	Warrants	exercise price		remaining life
	outstanding	per share		(yrs.)	Intrinsic value
As of December 31, 2017	6,514,625	$	1.92	1.6	$	—
As of December 31, 2018	6,514,625	$	1.92	0.6	$	—
As of March 31, 2019	6,514,625	$	1.92	0.4	$	—

These warrants will expire in August 2019.

Stock-Based Compensation

Under the Company’s stock option plan (the “Plan”), we may grant options to purchase common shares of the Company (“Common Shares”) to our directors, officers, employees and consultants. The maximum number of Common Shares that may be reserved for issuance under the Plan, together with the Company’s restricted share units (“RSUs”) currently outstanding under the Company’s long term incentive plan (“LTIP”), is a variable number equal to 10% of the issued and outstanding Common Shares on a non-diluted basis at any one time. Options under the Plan are granted from time to time at the discretion of the Board of Directors of the Company (“Board”), with vesting periods and other terms as determined by the Board.

Stock-based compensation expense for the three months ended March 31, 2019 and 2018 is as follows:


		Three Months Ended March 31,
	2019		2018
Stock options	$	50	$	146
Restricted stock units		1		192
	$	51	$	338

Phantom units (Discussed below)		22		—

RSU costs in the three months ended March 31, 2019 are reduced by the cumulative effect of certain forfeitures that occurred in the period.

As of March 31, 2019, stock options, RSUs, and phantom units had unrecognized compensation expense of $109, $108, and $135 respectively, which is expected to be recognized over a weighted average period of 1.1, 0.7, and 1.3 years, respectively.

Stock Options

A summary of options under the Plan as of March 31, 2019 is set forth in the following table:


				Weighted average
		Weighted average		remaining	Aggregate
	Number of	exercise price		contractual term	intrinsic
	options	per option		(years)	value
Outstanding - December 31, 2017	1,144,500		0.42	1.15	$	346
Granted	1,142,000		0.71
Exercised	(218,600)		0.39			36
Cancelled/Forfeited	(748,751)		0.36			—
Outstanding - December 31, 2018	1,319,149	$	0.71	3.84	$	1
Exercised	(127,000)		0.52			29
Cancelled/Forfeited	(149)		0.52			—
Outstanding - March 31, 2019	1,192,000	$	0.73	3.98	$	22

Exercisable - March 31, 2019	718,997	$	0.75	3.89	$	8

A summary of unvested stock options as of March 31, 2019 is set forth in the following table:


				Weighted
		Weighted		average
		average		remaining
		grant-date		amortization
	Number of	fair value		period
	options	per option		(years)
Unvested - December 31, 2017	246,250		0.22	0.99
Granted	1,142,000		0.45
Cancelled/Forfeited	(246,250)		0.22
Vested	(382,331)		0.45
Unvested - December 31, 2018	759,669	$	0.45	1.14
Vested	(286,666)		0.48
Unvested - March 31, 2019	473,003	$	0.44	1.08

No stock options were granted for the three months ended March 31, 2019. The fair value of stock options granted during the three months ended March 31, 2018 to employees, directors and consultants was estimated at the grant date using the Black-Scholes option pricing model using the following assumptions:



	2018
Expected volatility	76.2	%
Risk-free interest rate	2.7	%
Expected life (years)	5
Dividend yield	0
Forfeiture assumption	—	%

Option Amendment

In July 2018, the Company amended certain 2013 stock option agreements, expiring December 30, 2018 subject to the potential for a temporary extension under the terms of the Plan, for seven executives and directors (the “Option Amendment”). The amendment provided each grantee with the opportunity to receive a cash buyout of certain vested, unexercised 2013 options in lieu of exercising the option to purchase shares. This cash buyout was based on the intrinsic value of each option at the time of the buyout. Options exchanged for cash under the Option Amendment are considered canceled/forfeited.

Restricted Stock Units

The following table summarizes the RSUs outstanding under the LTIP as of March 31, 2019:


		Weighted average
	Number	grant-date fair
	of RSUs	value per RSU
Unvested - December 31, 2017	1,567,907	$	0.85
Cancelled/forfeited	(246,683)		0.90
Vested, net of shares withheld	(637,554)		0.88
Granted	319,000		0.75
Unvested - December 31, 2018	1,002,670	$	0.78
Cancelled/forfeited	(198,821)		0.76
Vested, net of shares withheld	(142,380)		0.75
Unvested - March 31, 2019	661,469	$	0.80

A portion of the RSU awards vest on a fixed future date provided the recipient continues to be affiliated with Vista on that date. Other RSU awards vest subject to certain performance and market criteria, including the accomplishment of certain corporate objectives and the Company’s share price performance. The minimum vesting period for RSUs is one year.

During the three months ended March 31, 2019, the Company withheld Common Shares with an equivalent value to meet the employee withholding tax obligations which resulted from RSUs that vested in the period. Common Shares withheld are considered cancelled/forfeited.

New RSUs will not be granted under the LTIP until the allocation of such awards is duly approved by the shareholders of the Company.

Phantom Units


		Weighted average
		remaining
	Number of	vesting term
	phantom units	(years)
Unvested - December 31, 2017	—
Granted	265,000
Unvested - December 31, 2018	265,000	1.50
Granted	—
Unvested - March 31, 2019	265,000	1.25

The Company granted a total of 265,000 phantom units to certain employees. The value of each unit is equal to the Company’s share price on the vesting date and is payable in cash. The phantom units vest on fixed future dates provided the recipient continues to be affiliated with Vista on those dates. The Company will account for these units as awards classified as liabilities with $45 included in current liabilities as of March 31, 2019. The Company recognized $22 of compensation expense for these phantom units in the three months ended March 31, 2019.