On May 6, 2019 (the Effective Date) the stockholders approved our 2019 Long-Term Incentive Plan (the 2019 Plan). The total amount of PotlatchDeltic common stock authorized for issuance under the 2019 Plan includes, in addition to 1.2 million new shares approved by our stockholders: (i) the total number of shares available for future awards under the Potlatch Corporation 2014 Long-Term Incentive Plan and its predecessor plans (the Prior Plans) as of the Effective Date and (ii) the number of undelivered shares subject to outstanding awards under the Prior Plans that will become available for future issuance as provided for under the 2019 Plan. At June 30, 2019, approximately 1.5 million shares are available for future use under our long-term incentive plans.

Share-based compensation activity during the six months ended June 30, 2019 included the following:

(Shares in thousands)	Granted		Vested		Forfeited
Performance Share Awards (PSAs)		142		—		5
Restricted Stock Units (RSUs)		74		17		2

A total of 0.3 million shares of common stock were issued during the six months ended June 30, 2019 as a result of RSU and PSA vesting during 2018 and 2019.

The following table details equity-based compensation expense and the related income tax benefit.

	Three Months Ended June 30,				Six Months Ended June 30,
(in thousands)	2019		2018		2019		2018
Equity-based compensation expense:
Performance share awards	$	1,187	$	1,074	$	2,231	$	2,010
Restricted stock units		629		454		1,187		934
Deferred compensation stock equivalent units expense		15		53		31		181
Accelerated share-based termination benefits in connection with the merger		—		86		—		1,764
Total equity-based compensation expense	$	1,831	$	1,667	$	3,449	$	4,889

Total tax benefit recognized for equity-based expense	$	83	$	73	$	155	$	184

PSAs granted under the stock incentive plans have a three-year performance period and shares are issued at the end of the period if the performance measures are met. The performance measures are based on the percentile ranking of our total shareholder return relative to the total shareholder return performance of both a selected peer group of companies and a larger group of indexed companies over the three-year performance period. The number of shares actually issued, as a percentage of the amount subject to the PSA, could range from 0% to 200%. PSAs granted under our stock incentive plans do not have voting rights unless and until shares are issued upon settlement. If shares are issued at the end of the three-year performance measurement period, the recipients will receive dividend equivalents in the form of additional shares at the time of payment equal to the dividends that would have been paid on the shares earned had the recipients owned the shares during the three-year period. Therefore, the shares are not considered participating securities. The fair value of performance shares granted in 2019 was $37.87 per share.

The following table presents the key inputs used in the Monte Carlo simulation to calculate the fair value of the performance share awards in 2019:

RSU awards accrue dividend equivalents based on dividends paid during the RSU vesting period. The dividend equivalents will be converted into additional RSUs that will vest in the same manner as the underlying RSUs to which they relate. Therefore, the shares are not considered participating securities. The terms of the awards state that the RSUs will vest in a given time period of one to three years and the terms of certain awards follow a vesting schedule within the given time period. The fair value of RSUs granted equaled our common share price on the date of grant. The weighted average fair value of all RSUs granted during the six months ended June 30, 2019 was $36.15.