6. Additional Paid-in Capital

Warrants

Warrant activity is summarized in the following table:


	Warrants outstanding		Weighted average exercise price per share	Weighted average remaining life (yrs.)		Intrinsic value

As of December 31, 2014	15,219,802	$	5.00	0.8	$	-
As of March 31, 2015	15,219,802	$	5.00	0.6	$	-

The 15,219,802 warrants outstanding expire in October 2015.

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 our 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, 2015 and 2014 is as follows:


		Three months ended March 31,
		2015		2014

Stock options	$	2	$	104
Restricted stock units		226		310
	$	228	$	414

As of March 31, 2015, stock options and RSUs had unrecognized compensation expense of $25 and $673, respectively, which is expected to be recognized over a weighted average period of 3.75 and 1.25 years, respectively.

Stock Options

A summary of option activity under the Plan as of March 31, 2015 and changes during the period then ended is set forth in the following table:


	Number of options		Weighted average exercise price per option	Weighted average remaining contractual term		Aggregate intrinsic value
Outstanding - December 31, 2014	2,257,500	$	1.60	3.02	$	-
Outstanding - March 31, 2015	2,257,500	$	1.60	2.78	$	-

Exercisable - March 31, 2015	2,011,250	$	1.75	2.66	$	-

A summary of our unvested stock options as of March 31, 2015 and changes during the period then ended is set forth in the following table:


	Number of options		Weighted average grant-date fair value per option	Weighted average remaining amortization period (Years)
Unvested - December 31, 2014	246,250	$	0.22	3.99
Unvested - March 31, 2015	246,250	$	0.22	3.75

Restricted Stock Units

The following table summarizes the RSU activity under the LTIP as of March 31, 2015 and changes during the years then ended:


	Number of units		Weighted average grant-date fair value per unit
Unvested - December 31, 2014	3,692,829	$	0.74
Unvested - March 31, 2015	3,692,829	$	0.74

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. The average forfeiture is approximately 29%, based on historical market conditions.