The Company awards equity-based compensation to employees and directors, which is recognized in the statements of operations based on the grant-date fair value of the award. The Company uses the straight-line method for recording compensation expense over a vesting period generally up to four years with either graded or cliff vesting. Stock compensation expense recognized during the period is based on the value of the portion of equity-based awards that is ultimately expected to vest during the period reduced by the expense on unvested awards forfeited during the period.

On May 4, 2018, the shareholders of the Company approved the adoption of the Gibraltar Industries, Inc. 2018 Equity Incentive Plan (the "2018 Plan"). The 2018 Plan provides for the issuance of up to 1,000,000 shares of common stock and supplements the remaining shares available for issuance under the existing Gibraltar Industries, Inc. 2015 Equity Incentive Plan (the "2015 Plan"). The Company's 2005 Equity Incentive Plan (the "Prior Plan") was amended in 2015 to terminate issuance of further awards from the Prior Plan.

Both the 2018 Plan and the 2015 Plan allow the Company to grant equity-based incentive compensation awards, in the form of non-qualified options, restricted shares, restricted stock units, performance shares, performance stock units, and stock rights to eligible participants.

In 2016, the shareholders of the Company approved the adoption of the Gibraltar Industries, Inc. 2016 Stock Plan for Non-Employee Directors ("Non-Employee Directors Plan") which allows the Company to grant awards of shares of the Company's common stock to non-employee Directors of the Company and permits the Directors to defer receipt of such shares pursuant to the terms of the Non-Employee Directors Plan.

At December 31, 2021, approximately 393,000 and 120,000 shares were available for issuance under the 2018 Plan and 2015 Plan, respectively, as incentive stock options or other stock awards, and approximately 19,000 shares were available for issuance under the Non-Employee Directors Plan as awards of shares of the Company's common stock.

The Company recognized the following compensation expense in connection with awards that vested under the 2018 Plan, the 2015 Plan, the Prior Plan, and the Non-Employee Directors Plan along with the related tax benefits recognized during the years ended December 31 (in thousands):


	2021		2020		2019
Expense recognized under the Prior Plan	$	29	$	40	$	192
Expense recognized under the 2015 Plan	1,186		1,932		5,077
Expense recognized under the 2018 Plan	6,597		5,441		6,731
Expense recognized under the Non-Employee Directors Plan	840		760		570
Total stock compensation expense	$	8,652	$	8,173	$	12,570
Tax benefits recognized related to stock compensation expense	$	2,189	$	2,272	$	3,136


	2021			2020			2019
Awards	Number of Awards	Weighted Average Grant Date Fair Value		Number of Awards	Weighted Average Grant Date Fair Value		Number of Awards	Weighted Average Grant Date Fair Value


Deferred stock units	7,536	$	83.58	12,402	$	45.98	7,509	$	37.95
Common stock	2,512	$	83.58	4,134	$	45.98	7,509	$	37.95
Restricted stock units	72,243	$	79.28	81,397	$	56.81	152,472	$	39.73
Performance stock units	62,778	$	87.84	160,426	$	55.98	183,908	$	40.49

No options were granted in 2021, 2020 and 2019. The Company determines the fair value of stock options granted based on the Black-Scholes option pricing model on the date of grant, and the expected stock volatility is based on volatility of the Company’s stock price using a historical period commensurate with the expected life of the options.


Range of Exercise Prices	Options Outstanding	Weighted Average Remaining Contractual Life (in years)	Weighted Average Exercise Price		Options Exercisable	Weighted Average Exercise Price


$39.00– $44.00	5,000	5.33	$	39.55	5,000	$	39.55


	Options	Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value
Balance at January 1, 2019	159,759	$	17.70

Exercised	(42,350)	11.57

Balance at December 31, 2019	117,409	$	19.91


Exercised	(75,909)	14.73
Balance at December 31, 2020	41,500	$	29.38
Exercised	(36,500)	27.99
Balance at December 31, 2021	5,000	$	39.55	5.33	$	135,650

The aggregate intrinsic value in the preceding table represents the total pre-tax intrinsic value, based on the $66.68 per share market price of the Company’s common stock as of December 31, 2021, which would have been received by the option holders had all option holders with an exercise price below the per share market price on December 31, 2021, exercised their options as of that date.


	Restricted Stock Units	Weighted Average Grant Date Fair Value		Common Stock	Weighted Average Grant Date Fair Value		Performance Stock Units (1) (2)	Weighted Average Grant Date Fair Value		Deferred Stock Units (3)	Weighted Average Grant Date Fair Value
Balance at December 31, 2020	237,442	$	41.15	—	$	—	407,289	$	45.00	47,154	$	37.30
Granted	72,243	$	79.28	2,512	$	83.58	62,778	$	87.84	7,536	$	83.58
Adjustments	—	$	—	—	$	—	7,400	$	52.40	—	$	—
Vested	(83,028)	$	43.09	(2,512)	$	83.58	(106,826)	$	35.06	(2,218)	$	36.47
Forfeited	(22,073)	$	49.78	—	$	—	(7,167)	$	46.87	—	$	—
Balance at December 31, 2021	204,584	$	52.90	—	$	—	363,474	$	55.44	52,472	$	43.99

(1) The Company’s performance stock units (“PSUs”) represent shares granted for which the final number of shares earned depends on financial performance or market conditions. The number of shares to be issued may vary between 0% and 200% of the number of PSUs granted depending on the relative achievement to targeted thresholds. The Company's PSUs with a financial performance condition are based on either the Company’s return on invested capital (“ROIC”) over a one-year period performance period or other criteria such as revenue, gross profit, and operating profit thresholds over a two-year or three-year performance period. The Company's PSUs with a market condition are based on the ranking of the Company’s total shareholder return (“TSR”) performance, on a percentile basis, over a three year performance period compared to the S&P Small Cap Industrial sector, over the same three year performance period.

(2) The Company's PSU adjustments during 2021 represent shares earned for achievement in excess of targeted thresholds at the end of the performance period. The Company's PSUs with a financial performance condition, based on the Company ROIC, granted in 2020 accounted for the 7,400 PSUs that will be converted to shares and issued to recipients in the first quarter of 2023 at 109.5% of the target amount granted, based on the Company's actual ROIC compared to ROIC target for the performance period ended December 31, 2020.

The fair value of the common stock, restricted stock units, and deferred stock units, as well as the performance stock units with a financial performance condition granted during the three years ended December 31, 2021 was based on the Company stock price at grant date of the award. The fair value of the performance stock units with a market condition granted during the three years ended December 31, 2021 were determined using a Monte Carlo simulation as of the grant date of the award. The Company granted performance units with a market condition during 2020, however, no such awards were granted in 2021 and 2019.

The following table sets forth the aggregate intrinsic value of options exercised and aggregate fair value of restricted stock units and restricted shares that vested during the years ended December 31 (in thousands):


	2021		2020		2019
Aggregate intrinsic value of options exercised	$	2,103	$	3,812	$	1,371
Aggregate fair value of vested restricted stock units	$	6,320	$	11,851	$	10,017
Aggregate fair value of vested common and restricted shares	$	370	$	190	$	285
Aggregate fair value of vested deferred stock units	$	630	$	570	$	285

As of December 31, 2021, there was $10.3 million of total unrecognized compensation cost related to non-vested restricted and performance stock units. That cost is expected to be recognized over a weighted average period of 2.1 years.

At December 31, 2021, the Company's equity based awards that are settled in cash are the awards under the Management Stock Purchase Plan ("MSPP"). The total of these share-based liabilities recorded on the consolidated balance sheet as of December 31, 2021 was $22.6 million, of which $2.9 million was included in current accrued expenses and $19.7 million was included in non-current liabilities. Total share-based liabilities as of December 31, 2020 were $18.2 million, of which $14.7 million was included in non-current liabilities.

The MSPP provides participants the ability to defer a portion of their compensation, convertible to unrestricted investments, restricted stock units, or a combination of both, or defer a portion of their Directors’ fees, convertible to restricted stock units. Employees eligible to defer a portion of their compensation also receive a company-matching award in restricted stock units equal to a percentage of their deferred compensation.

The deferrals and related company match are credited to an account that represents a share-based liability. The portion of the account deferred to unrestricted investments is measured at fair market value of the unrestricted investments, and the portion of the account deferred to restricted stock units and company-matching restricted stock units is measured at a 200-day average of the Company stock price. The account will be converted to and settled in cash payable to participants upon retirement or a termination of their service to the Company.

The following table provides the number of restricted stock units credited to active participant accounts, balance of vested and unvested restricted stock units within active participant accounts, payments made with respect to restricted stock units issued under the MSPP, and MSPP expense during years ended December 31:


	2021		2020		2019
Restricted stock units credited	30,475		57,046		61,369
Restricted stock units balance, vested and unvested	223,892		231,343		415,760
Share-based liabilities paid, in thousands	$	4,915	$	15,401	$	6,543
MSPP expense, in thousands	$	6,034	$	4,518	$	2,699