In 2012, our Board of Directors adopted and stockholders approved the Realty Income Corporation 2012 Incentive Award Plan, or the 2012 Plan, to enable us to motivate, attract and retain the services of directors and employees considered essential to our long-term success. The 2012 Plan offers our directors and employees an opportunity to own our stock or rights that will reflect our growth, development and financial success. Under the terms of the 2012 plan, the aggregate number of shares of our common stock subject to options, restricted stock, stock appreciation rights, restricted stock units and other awards, will be no more than 3,985,734 shares. The 2012 Plan has a term of ten years from the date it was adopted by our Board of Directors.

The amount of share-based compensation costs recognized in general and administrative expense on our consolidated statements of income and comprehensive income was $13.7 million during 2019, $27.3 million during 2018 (including $11.8 million of accelerated equity awards for our former CEO upon his departure from the company), and $13.9 million during 2017.

In October 2018, John P. Case departed as our Chief Executive Officer (CEO) and resigned as a member of our Board of Directors. In connection with his departure, we entered into a severance agreement with Mr. Case. Pursuant to the terms of this severance agreement, Mr. Case received a severance payment, which included both cash and stock compensation components. The total value of cash, stock compensation and professional fees incurred as a result of this severance was $28.3 million; however, the net amount, after incorporating accruals for CEO compensation previous to this severance, was $18.7 million, which was recognized in general and administrative expense on our 2018 consolidated statement of income and comprehensive income, and which represents the incremental costs incurred per the reconciliation below (dollars in thousands):



Cash	$	9,817
Stock compensation	17,902
Professional fees	574
Total value of severance	28,293
Amount accrued for CEO compensation prior to separation	(9,642		)
Incremental severance	$	18,651



	2019				2018				2017
	Number of shares		Weighted average price⁽¹⁾		Number of shares		Weighted average price⁽¹⁾		Number of shares		Weighted average price⁽¹⁾
Outstanding nonvested shares, beginning of year	307,821		$	53.44	475,768		$	52.32	513,523		$	48.33
Shares granted	87,327		$	69.83	183,952		$	52.21	149,264		$	59.21
Shares vested	(126,363	)	$	54.45	(310,706	)	$	51.05	(183,381	)	$	46.65
Shares forfeited	(9,087	)	$	55.71	(41,193	)	$	53.06	(3,638	)	$	56.57
Outstanding nonvested shares, end of each period	259,698		$	58.39	307,821		$	53.44	475,768		$	52.32

During May 2019, we granted 32,000 shares of common stock to the independent members of our Board of Directors, of which 20,000 shares vested immediately, 4,000 shares vest over a one-year service period, and 8,000 shares vest in equal parts over a three-year service period. In addition, in November 2019, we granted 4,000 shares of common stock to the new member of our Board of Directors, which vests in equal parts over a three-year service period.

Shares granted to employees typically vest annually in equal parts over a four-year service period. During 2019, 51,327 shares were granted to our employees, and vest over a four-year service period.

As of December 31, 2019, the remaining unamortized share-based compensation expense related to restricted stock totaled $10.1 million, which is being amortized on a straight-line basis over the service period of each applicable award. The amount of share-based compensation is based on the fair value of the stock at the grant date. We define the grant date as the date the recipient and Realty Income have a mutual understanding of the key terms and conditions of the award, and the recipient of the grant begins to benefit from, or be adversely affected by, subsequent changes in the price of the shares.

During 2019, 2018 and 2017, we granted performance share awards, as well as dividend equivalent rights, to our executive officers. The number of performance shares that vest for each of the three years is based on the achievement of the following performance goals:



Performance Awards Metrics	Weighting
Total shareholder return (“TSR”) relative to MSCI US REIT Index	45	%
TSR relative to JP Morgan Net Lease Peers	26	%
Dividend per share growth rate	16	%
Debt-to-EBITDA ratio	13	%

The performance shares are earned based on our performance, and vest 50% on the first and second January 1 after the end of the three-year performance period, subject to continued service. The performance period for the 2017 performance awards began on January 1, 2017 and ended on December 31, 2019. The performance period for the 2018 performance awards began on January 1, 2018 and will end on December 31, 2020. The performance period for the 2019 performance awards began on January 1, 2019 and will end on December 31, 2021.

The fair value of the performance shares was estimated on the date of grant using a Monte Carlo Simulation model. The following table summarizes our performance share grant activity:



	2019				2018				2017
	Number of performance shares		Weighted average price⁽¹⁾		Number of performance shares		Weighted average price⁽¹⁾		Number of performance shares		Weighted average price⁽¹⁾
Outstanding nonvested shares, beginning of year	223,392		$	58.78	245,309		$	62.49	159,751		$	49.95
Shares granted	128,581		$	65.34	269,868		$	51.98	124,681		$	71.79
Shares vested	(47,310	)	$	54.27	(291,785	)	$	54.88	(39,123	)	$	41.60
Shares forfeited	—		$	—	—		$	—	—		$	—
Outstanding nonvested shares, end of each period	304,663		$	62.25	223,392		$	58.78	245,309		$	62.49

As of December 31, 2019, the remaining share-based compensation expense related to the performance shares totaled $8.7 million and is being recognized on a tranche-by-tranche basis over the service period.

During 2019, 2018 and 2017 we also granted restricted stock units that primarily vest over a four-year service period and have the same economic rights as shares of restricted stock:



	2019				2018				2017
	Number of restricted stock units		Weighted average price⁽¹⁾		Number of restricted stock units		Weighted average price⁽¹⁾		Number of restricted stock units		Weighted average price⁽¹⁾
Outstanding nonvested shares, beginning of year	14,968		$	54.62	24,869		$	55.97	18,460		$	52.65
Shares granted	5,482		$	69.58	8,383		$	49.96	10,467		$	60.56
Shares vested	(4,939	)	$	54.90	(10,118	)	$	55.01	(4,058	)	$	52.70
Shares forfeited	—		$	—	(8,166	)	$	53.45	—		$	—
Outstanding nonvested shares, end of each period	15,511		$	59.82	14,968		$	54.62	24,869		$	55.97

The amount of share-based compensation for the restricted stock units is based on the fair value of our common stock as the grant date. As of December 31, 2019, the remaining share-based compensation expense related to the restricted stock units totaled $296,000 and is being recognized on a straight-line basis over the service period.