6. Common Shares

Warrants

All outstanding warrants totaling 6,514,625 expired unexercised in August 2019.

Stock-Based Compensation

The Company’s stock-based compensation plans include: restricted share units (“RSUs”) currently outstanding under the Company’s long term equity incentive plan (“LTIP”), deferred share units (“DSUs”) issuable pursuant to the Company’s deferred share unit plan (“DSU Plan”) and stock options (“Stock Options”) issuable under the Company’s stock option plan (the “Plan”). Stock-based compensation may be issued to our directors, officers, employees and consultants. The maximum number of Common Shares that may be reserved for issuance under these stock-based compensation plans is a variable number equal to 10% of the issued and outstanding Common Shares on a non-diluted basis at any one time. Vista also issued phantom units in 2018 to be settled in cash. Stock-based compensation and phantom units may be granted from time to time at the discretion of the Board of Directors of the Company (the “Board”), with vesting provisions as determined by the Board.

Stock-based compensation expense for the three months ended March 31, 2020 and 2019 was:


		Three Months Ended March 31,
	2020		2019
Restricted share units		151		1
Deferred share units		209		—
Stock Options	$	30	$	50
	$	390	$	51

Phantom units	$	(1)	$	22

As of March 31, 2020, unrecognized compensation expense for RSUs, Stock Options, and phantom units was $776, $24, and $42, respectively, which is expected to be recognized over weighted average periods of 1.5, 0.6, and 0.8 years, respectively.

Restricted Share Units

The following table summarizes the RSUs outstanding under the LTIP as of March 31, 2020:


		Weighted average
	Number	grant-date fair
	of RSUs	value per RSU
Unvested - December 31, 2018	1,002,670	$	0.78
Granted	1,412,500		0.49
Cancelled/forfeited	(657,573)		0.76
Vested, net of shares withheld	(266,296)		0.84
Unvested - December 31, 2019	1,491,301	$	0.51
Granted	1,609,000		0.41
Unvested - March 31, 2020	3,100,301	$	0.46

No RSU vesting events occurred during the three months ended March 31, 2020. During the three months ended March 31, 2019, the Company withheld Common Shares with an equivalent value to meet employee withholding tax obligations that resulted upon vesting of RSUs during the period. Common Shares withheld are considered cancelled/forfeited.

Deferred Share Units

The DSU Plan provides for granting of DSUs to non-employee directors. DSUs vest immediately, however the Company will issue one Common Share for each DSU only after the non-employee director has ceased to be a director of the Company. During the three months ended March 31, 2020, the Board granted 360,000 DSUs and the Company recognized $209 in DSU expense.

The following table summarizes the DSUs outstanding as of March 31, 2020:



		Weighted average
	Number of	grant-date fair
	DSUs	value per DSU
Unvested - December 31, 2018	—	—
Granted	366,000	0.57
Outstanding - December 31, 2019	366,000	0.57
Granted	360,000	0.58
Outstanding - March 31, 2020	726,000	0.57

Stock Options

A summary of stock options as of March 31, 2020 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, 2018	1,319,149		0.71	3.84	$	1
Granted	350,000		0.73
Exercised	(163,667)		0.54			33
Cancelled/Forfeited	(16,667)		0.75			—
Expired	(51,815)		0.70			2
Outstanding - December 31, 2019	1,437,000	$	0.73	3.49	$	35
Cancelled/Forfeited	(70,000)		1.02			—
Outstanding - March 31, 2020	1,367,000	$	0.72	3.31	$	—

Exercisable - March 31, 2020	1,103,001	$	0.72	3.18	$	—

A summary of unvested stock options as of March 31, 2020 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, 2018	759,669	$	0.45	1.14
Granted	350,000		0.30
Cancelled/Forfeited	(35,000)		0.43
Vested	(560,665)		0.41
Unvested - December 31, 2019	514,004	$	0.40	0.61
Vested	(250,005)		0.48
Unvested - March 31, 2020	263,999	$	0.32	0.58

The fair value of stock options granted is estimated at the grant date using the Black-Scholes option pricing model. No option grants were made during the three months ended March 31, 2020.

Phantom Units

A summary of unvested phantom units as of March 31, 2020 is set forth in the following table:


		Weighted average
		remaining
	Number of	vesting term
	phantom units	(years)
Unvested - December 31, 2018	265,000
Cancelled/forfeited	(32,667)
Vested	(88,333)
Unvested - December 31, 2019	144,000	1.00
Unvested - March 31, 2020	144,000	0.75