Stock options are granted under the Company’s long-term incentive plan and have an exercise price that may not be less than the fair market value of the underlying shares on the date of grant. In general, stock options granted to participants will become exercisable over a period determined by the Compensation Committee of the Company’s Board of Directors, which in the past has been a five year term, with the options vesting over a service period of two to five years.  A portion of the stock options granted in the three months ended March 31, 2015 and 2014 were vested immediately with the remainder vesting over a two year period. In addition, stock options will become exercisable upon a change in control, unless provided otherwise by the Compensation Committee of our Board of Directors. At March 31, 2015, there were 2,954,293 shares subject to options authorized but not granted under the 2014 Long Term Incentive Plan and 212,065 shares authorized under the prior existing long term incentive plans from which no options can be granted.

For the three months ended March 31, 2015 and 2014, the Company recognized non-cash compensation expense of $1.7 million and $1.4 million, respectively, related to stock-based compensation. These amounts were recorded as general and administrative expense. Because the Company does not pay significant United States federal income taxes, no amounts were recorded for tax benefits.

A summary of the stock option activity for the three months ended March 31, 2015 is provided below:

The intrinsic value of a stock option is the amount by which the current market value of the underlying stock exceeds the exercise price of the option.

In the three months ended March 31, 2015, the Company repurchased 114,985 shares at an average price of $4.98 per shares totaling $0.6 million. The shares repurchased were related to options exercised by employees which are approved under the long term incentive plans as disclosed in our proxy filings. The Company did not repurchase any shares in the three months ended March 31, 2014.

Shares of restricted stock are granted under the Company’s long-term incentive plan using the fair market value of the underlying shares on the date of grant. In general, restricted stock granted to employees will vest over a period determined by the Compensation Committee which is generally a three year period, vesting in three equal parts on the first three anniversaries of the date of the grant.

There were restricted stock grants in the three months ended March 31, 2015. A summary of the restricted stock activity for the three months ended March 31, 2015 is provided below:

As of March 31, 2015, unrecognized compensation costs totaled $4.8 million. The expense is expected to be recognized over a weighted average period of 2.43 years.