6. Common Shares

Stock-Based Compensation

Under our Stock Option Plan (the “Plan”) and our Long-Term Equity Incentive Plan (the “LTIP”), we may grant options and/or restricted stock units (“RSUs”) or restricted stock awards to our directors, officers, employees and consultants. The combined maximum number of shares in the capital of Vista (“Common Shares”) that may be reserved for issuance under the Plan and the LTIP is a variable number equal to 10% of the issued and outstanding Common Shares on a non-diluted basis. Options and RSUs under the Plan and LTIP, respectively, 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, 2016 and 2015 is as follows:


	Three Months Ended March 31,
	2016		2015
Stock options	$	2	$	2
Restricted stock units		140		226
	$	142	$	228

As of March 31, 2016, stock options and RSUs had unrecognized compensation expense of $21 and $438, respectively, which is expected to be recognized over a weighted average period of 2.75 and 0.98 years, respectively.

Stock Options

A summary of options under the Plan as of March 31, 2016 is set forth in the following table:


		Weighted average		Weighted average	Aggregate
	Number of	exercise price		remaining	intrinsic
	options	per option		contractual term	value
Outstanding - December 31, 2015	2,257,500	$	1.60	2.02	$	—
Outstanding - March 31, 2016	2,257,500	$	1.60	1.77	$	108

Exercisable - March 31, 2016	2,011,250	$	1.75	1.65	$	81

A summary of our unvested stock options as of March 31, 2016 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, 2015	246,250	$	0.22
Unvested - March 31, 2016	246,250	$	0.22	2.75

Restricted Stock Units

The following table summarizes the RSUs under the LTIP as of March 31, 2016:


		Weighted average
	Number	grant-date fair
	of units	value per unit
Unvested - December 31, 2015	4,085,446	$	0.44
Vested	(20,570)		1.68
Granted	483,000		0.52
Unvested - March 31, 2016	4,547,876	$	0.44

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 vesting period for RSUs is at least one year.