The Company’s stock-based compensation has been granted under several stock incentive and long-term incentive plans. The plans authorize the Compensation Committee of the Company’s Board of Directors to issue various types of incentive compensation. Currently, the Company has issued stock options and restricted shares under the 2014 Long-Term Incentive Plan (“2014 Plan”) and stock appreciation rights under the 2016 Stock Appreciation Rights Plan. At June 30, 2019, 373 shares were authorized for future grants under the 2014 plan.

For each stock option granted, the number of authorized shares under the 2014 Plan will be reduced on a one-for-one basis. For each restricted share granted, the number of shares authorized under the 2014 Plan will be reduced by twice the number of restricted shares. The Company has no set policy for sourcing shares for option grants. Historically the shares issued under option grants have been new shares.

The Company records compensation expense related to stock-based compensation as general and administrative expense. For the three months ended June 30, 2019 and 2018, stock-based compensation was $(0.1) million and $2.4 million, respectively, related to the issuance of stock options, restricted stock and stock appreciation rights. For the six months ended June 30, 2019 and 2018, stock-based compensation was $1.6 million and $2.8 million, respectively, related to the issuance of stock options, restricted stock and stock appreciation rights. During the six months ended June 30, 2019 and 2018, the Company settled in cash $0.3 million and $0.1 million, respectively, for stock appreciation rights exercises. Because the Company does not pay significant United States federal income taxes, no amounts were recorded for future tax benefits.

Stock options

Stock options 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 life, with the options vesting over a service period of up to

The following is a summary of activity for the six months ended June 30, 2019:

During the three and six months ended June 30, 2019, 30,573 shares were added to treasury as a result of tax withholding on the vesting of restricted shares. During the three and six months ended June 30, 2018, 35,265 shares were added to treasury as a result of tax withholding on the vesting of restricted shares.

Stock appreciation rights (“SARs”)

SARs are granted under the VAALCO Energy, Inc. 2016 Stock Appreciation Rights Plan. A SAR is the right to receive a cash amount equal to the spread with respect to a share of common stock upon the exercise of the SAR. The spread is the difference between the SAR price per share specified in a SAR award on the date of grant (which may not be less than the fair market value of the Company’s common stock on the date of grant) and the fair market value per share on the date of exercise of the SAR. SARs granted to participants will become exercisable over a period determined by the Compensation Committee of the Company’s Board of Directors. In addition, SARs will become exercisable upon a change in control, unless provided otherwise by the Compensation Committee of the Company’s Board of Directors.

On February 28, 2019, 951,699 SARs were granted which vest over a three-year period with a life of 5 years and have a $2.33 SAR price per share specified in a SAR award on the date of grant. On May 10, 2019, 196,892 SARs were granted which vest over a three-year period with a life of 5 years and have a $1.72 SAR price per share specified in a SAR award on the date of grant.

SAR activity for the six months ended June 30, 2019 is provided below:

Other Benefit Plans