We issue new shares of common stock to settle performance stock awards (PSAs), restricted stock units (RSUs) and deferred compensation stock equivalent units. At December 31, 2021, approximately 0.9 million shares were available for future use under our long-term incentive plans.

The following table details our compensation expense and the related income tax benefit for the years ended December 31:


(in thousands)	2021		2020		2019
Employee equity-based compensation expense:
Performance stock awards	$	5,381	$	5,083	$	4,605
Restricted stock units		3,041		2,904		2,595
Deferred compensation stock equivalent units expense		185		76		72
Total equity-based compensation expense	$	8,607	$	8,063	$	7,272

Total tax benefit recognized for shared-based payment awards	$	428	$	357	$	314

During 2021, 2020 and 2019, officers and certain other employees of the company were granted PSA awards. 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. Performance shares are earned based on the company's total shareholder return (TSR) over a three-year performance period relative to the median TSR of performance peer group (weighted 50%) and the company's TSR percentile ranking relative to all companies within the NAREIT All Equity REITs Index (of which we are a member) (weighted 50%) over such performance period. TSR is calculated based on stock price appreciation plus cash and share distributions. 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.

Since the awards contain a market condition, the effect of the market condition is reflected in the grant-date fair value, which is estimated using a Monte Carlo simulation. This method is used to estimate the stock prices of PotlatchDeltic and the selected peer companies at the end of the three-year performance period. The Monte Carlo simulation uses inputs such as stock prices and expected volatility of PotlatchDeltic and the peer group of companies as of the award date. Multiple simulations are generated, resulting in share prices and total shareholder return values for PotlatchDeltic and the peer group of companies. For each simulation, the total shareholder return of PotlatchDeltic is ranked against that of the peer group of companies. The future value of the performance share unit is calculated based on a multiplier for the median outperformance and percentile ranking and then discounted to present value. The discount rate is the risk-free rate as of the award date for a term consistent with the performance period. Awards are also credited with dividend equivalents at the end of the performance period, and as a result, award values are not adjusted for dividends.

The following table presents the key inputs used in calculating the fair value of the PSAs and the resulting fair values:


	Year Ended December 31,
	2021			2020			2019
Stock price as of valuation date	$	53.53		$	42.16		$	35.01
Risk-free rate		0.18	%		1.42	%		2.47	%
Expected volatility		45.56	%		25.74	%		25.15	%
Expected dividend yield1		—			—			—
Expected term (years)		3.00			3.00			3.00
Fair value of a performance share	$	69.72		$	45.04		$	37.87


1	Full dividend reinvestment assumed.

The following table summarizes outstanding PSAs as of December 31 and the changes during each year:


	2021					2020					2019
(in thousands, except per share amounts)	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Nonvested shares outstanding at January 1		253,266		$	41.36		196,007		$	50.15		142,238		$	63.91
Granted		88,128		$	69.72		125,001		$	45.04		142,066		$	37.87
Vested		(129,666	)	$	37.87		(63,456	)	$	75.37		(75,048	)	$	53.85
Forfeited		(9,281	)	$	58.32		(4,286	)	$	47.07		(13,249	)	$	45.35
Nonvested shares outstanding at December 31		202,447		$	55.16		253,266		$	41.36		196,007		$	50.15
Total grant date fair value of PSA awards vested during the year	$	4,910				$	4,783				$	4,041
Total fair value of PSA awards vested during the year	$	12,015				$	3,968				$	3,561

As of December 31, 2021, there was $5.8 million of unrecognized compensation cost related to nonvested PSAs, which is expected to be recognized over a weighted average period of 1.4 years.

During 2021, 2020 and 2019, directors, officers, and certain other employees of the company were granted RSU awards that will vest from one to three years. RSU awards are credited with dividend equivalents for any dividends paid on the company's common stock during the vesting period. Recipients will receive dividend equivalents in the form of additional shares of common stock at the date the vested RSUs are settled. Any forfeited RSUs will not receive dividends. Therefore, the shares are not considered participating securities.

The following table summarizes outstanding RSU awards as of December 31 and the changes during each year:


	2021					2020					2019
(in thousands, except per share amounts)	Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value		Shares			Weighted Average Grant Date Fair Value
Nonvested shares outstanding at January 1		139,492		$	37.54		127,471		$	39.83		72,020		$	47.66
Granted		66,107		$	54.52		68,263		$	38.77		104,488		$	36.80
Vested		(68,606	)	$	34.50		(52,908	)	$	44.48		(43,102	)	$	45.51
Forfeited		(4,094	)	$	49.35		(3,334	)	$	40.20		(5,935	)	$	40.26
Nonvested shares outstanding at December 31		132,899		$	47.19		139,492		$	37.54		127,471		$	39.83
Total grant date fair value of RSU awards vested during the year	$	2,367				$	2,354				$	1,961
Total fair value of RSU awards vested during the year	$	4,130				$	2,196				$	1,771

As of December 31, 2021, there was $2.9 million of total unrecognized compensation cost related to nonvested RSU awards, which is expected to be recognized over a weighted average period of 1.3 years.

A long-term incentive award was granted annually to our directors through December 2017. The awards are payable upon a director's separation from service. Directors may also elect to defer their annual retainers, payable in the form of stock. Additionally, issuance of restricted stock units awarded to certain officers and employees may also be deferred. All stock unit equivalent accounts are credited with dividend equivalents. At December 31, 2021, shares outstanding that will be distributed in the future to directors or officers and employees as common stock were 174,559 and 7,247, respectively.