8. Additional Paid-in Capital


		Warrants		Stock options and RSUs		Other paid-in capital		Total additional paid-in capital

As of December 31, 2013	$	12,936	$	7,987	$	11,564	$	32,487
Warrants expired		(2,124)		-		2,124		-
Stock options amortization		-		158		-		158
Restricted stock units expensed		-		9		-		9
As of September 30, 2014	$	10,812	$	8,154	$	13,688	$	32,654

Warrants

Warrant activity is summarized in the following table:


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

As of December 31, 2013	19,977,743	$	12,936	$	4.63	1.6	$	-
Expired	(2,666,666)		(2,124)
As of September 30, 2014	17,311,077	$	10,812	$	4.79	1.0	$	-

The 17,311,077 outstanding warrants expire in the following time frames 2,091,275 expire December 2014 and 15,219,802 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 (“RSAs”) 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 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 (benefit) for the three and nine months ended September 30, 2014 and 2013 is as follows:


		Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013

Stock options	$	35	$	72	$	158	$	290
Restricted stock units		(616)		396		9		922
	$	(581)	$	468	$	167	$	1,212

The restricted stock cost recovery for the three months ended September 30, 2014 is due to the cancellation of RSUs that had been expensed in prior periods but did not satisfy the vesting conditions. As of September 30, 2014, stock options and RSUs had unrecognized compensation expense of $26 and $1,218, respectively, which is expected to be recognized over a weighted average period of 4.25 and 1.63 years, respectively.

Stock Options

A summary of option activity under the Plan as of September 30, 2014 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, 2013	2,882,500	$	1.79	3.07	$	54
Granted	175,000		0.52
Cancelled/Forfeited	(125,000)		3.16
Expired	(675,000)		1.85
Outstanding - September 30, 2014	2,257,500	$	1.60	3.27	$	59

Exercisable - September 30, 2014	2,011,250	$	1.75	3.15	$	44

A summary of our unvested stock options as of September 30, 2014 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, 2013	738,750	$	0.22
Granted	175,000
Vested	(667,500)
Unvested - September 30, 2014	246,250	$	0.22	4.25

The fair value of stock options granted to employees, directors and consultants was estimated at the grant date using the Black-Scholes option pricing model using the following assumptions:


		Nine Months Ended September 30, 2014
Expected volatility		69.17%
Risk-free interest rate		1.75%
Expected life (years)		5
Dividend yield		N/A
Forfeiture assumption		10%

Option pricing models require the input of highly subjective assumptions, including the expected price volatility. Expected price volatility is based on the historical volatility of our common shares. Changes in the subjective input assumptions can materially affect the fair value estimate. The expected term of the options granted represents the period of time that the options granted are expected to be outstanding. The risk-free rate for the periods within the contractual term of the option is based on the U.S. Treasury yield curve in effect at the date of grant.

Restricted Stock Units

The following table summarizes the RSU activity under the LTIP as of September 30, 2014 and changes during the years then ended:


	Number of units		Weighted average grant-date fair value per unit
Unvested - December 31, 2013	2,594,464	$	2.00
Cancelled/forfeited	(288,391)		3.23
Granted	2,079,000		0.46
Unvested - September 30, 2014	4,385,073	$	1.19

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 criteria, including the accomplishment of certain corporate objectives and the Company’s share price performance. The vesting period for time based RSUs is at least one year.