All share-based compensation cost is measured at the grant date, based on the estimated fair value of the award. The Company issues time-based, performance-based and market performance-based equity awards. Time-based and cliff vesting market performance-based awards are recognized on a straight-line basis over the employees’ requisite service period, as adjusted for estimate of forfeitures. Performance-based awards are recognized ratably over the vesting period using a graded vesting attribution model upon the achievement of the performance target, as adjusted for estimate of forfeitures. The only performance-based awards issued by the Company were granted in 2016 and 2017.

Aggregate share-based compensation charges were $15.9 million, $10.7 million and $2.4 million during the years ended December 31, 2019, 2018 and 2017, respectively. Approximately $12.8 million, $8.7 million and $2.4 million of these charges were considered routine share-based compensation expense, and were included as a component of “Selling, general and administrative” expense on the accompanying Consolidated Statements of Operations during the years ended December 31, 2019, 2018 and 2017, respectively. Approximately $3.1 million of share-based compensation expense was recorded during the year ended December 31, 2019 due to accelerated vesting of awards outstanding to former executives and an equity award modification upon trustee resignation, and were included as a component of “Acquisition, litigation and other” expense on the accompanying Consolidated Statements of Operations. Approximately $2.0 million of share-based compensation expense was recorded during the year ended December 31, 2018 as a result of modification to certain restricted stock units, and is included as a component of “Acquisition, litigation and other” expense on the accompanying Consolidated Statements of Operations. The award modifications and awards with accelerated vesting are discussed further under the section “Modification of Restricted Stock Units and Accelerated Vesting of Awards”. As of December 31, 2019, there was $24.7 million of unrecognized share‑based compensation expense related to stock options and restricted stock units, which will be recognized over a weighted-average period of 1.9 years.

During December 2008, the Company and the common shareholders approved the Americold Realty Trust 2008 Equity Incentive Plan (2008 Plan), whereby the Company may issue either stock options or stock appreciation rights based upon a reserved pool of 4,900,025 common shares. No additional awards may be granted under the 2008 Plan. During December 2010, the Company and the common shareholders approved the Americold Realty Trust 2010 Equity Incentive Plan (2010 Plan), whereby the Company could issue stock options, stock appreciation rights, restricted stock, restricted stock units, stock bonus awards, and/or dividend equivalents with respect to the Company’s common shares, cash bonus awards, and/or performance compensation awards to certain eligible participants, as defined, based upon a reserved pool of 3,849,976 of the Company’s common shares. No additional awards may be granted under the 2010 Plan.

On January 4, 2018, the Company’s Board of Trustees adopted the Americold Realty Trust 2017 Equity Incentive Plan (2017 Plan), which permits the grant of various forms of equity- and cash-based awards from a reserved pool of 9,000,000 common shares of the Company. On January 17, 2018, the Company’s shareholders approved the 2017 Plan. Equity-based awards issued under the 2017 Plan have the rights to receive dividend equivalents on an accrual basis. Dividend equivalents for market performance-based awards are forfeitable in the event of termination for cause or when voluntary departure occurs during the vesting period. Otherwise, dividend equivalents are accrued at the time of declaration and paid upon the vesting of the awards. Time-based awards have the right to receive nonforfeitable dividend equivalent distributions on unvested units throughout the vesting period. As of December 31, 2019 and 2018, the Company accrued $1.1 million and $0.4 million, respectively, of dividend equivalents on unvested units payable to employees and non-employee trustees.

On January 4, 2018, the Company’s Board of Trustees approved the modification of awards to allow the grant of dividend equivalents to all participants in the 2010 Plan with respect to any and all vested restricted stock units of the Company that have not been settled or converted to shares pursuant to the 2010 Plan. On the same day, the Company’s Board of Trustees resolved that no further awards may be granted under the 2010 Plan after the approval of the 2017 Plan. As a result, the Company recognized share-based compensation expense of $2.0 million to reflect the change in fair value associated with the modification of the dividend equivalents rights of the outstanding equity awards under the 2010 Plan.

During the first quarter of 2019, the Company’s Compensation Committee approved the modification of an award issued in 2018 to a member of the Board of Trustees upon his resignation. This modification immediately accelerated the next vesting tranche of 100,000 restricted stock units which otherwise would not have vested until 2020 assuming the trustee continued service, under the original award agreement. As a result of this modification, the Company recognized approximately $2.9 million of share-based compensation expense during the first quarter of 2019.

Restricted stock units are nontransferable until vested. Prior to the issuance of a common share, the grantees of restricted stock units are not entitled to vote the shares. Time-based restricted stock unit awards vest in equal annual increments over the vesting period. The grant date fair values for time-based restricted unit stock awards is equal to the closing market price of Americold Realty Trust common stock on the grant date. Performance-based and market performance-based restricted stock unit awards vest upon the achievement of the performance target, as well as completion of performance period.



Year Ended December 31	Grantee Type	Number of Restricted Stock Units Granted	Vesting Period	Grant Date Fair Value (in thousands)
2019	Trustees	18,267	1 year	$	575
2019	Employees	504,984	1-3 years	$	16,843
2018	Trustees	373,438	1-3 years	$	5,975
2018	Employees	1,263,751	1-4 years	$	22,196
2017	Trustees	18,348	2-3 years	$	199
2017	Employees	141,288	5 years	$	1,897

Of the restricted stock units granted for the year ended December 31, 2019, (i) 12,285 were time-based restricted stock units with a one-year vesting period issued to non-employee trustees in recognition of their efforts and oversight in the first year as a public company, (ii) 5,982 were time-based restricted stock units with a one-year vesting period issued to non-employee trustees as part of their annual compensation (iii) 261,816 were time-based graded vesting restricted stock units with various vesting periods ranging from one to three years issued to certain employees and

Of the restricted stock units granted for the year ended December 31, 2018, (i) 331,250 were time-based graded vesting restricted stock units with a three-year vesting period issued to non-employee trustees in connection with the IPO, (ii) 42,188 were time-based graded vesting restricted stock units with a one-year vesting period issued to non-employee trustees as part of their annual compensation, (iii) 659,751 were time-based graded vesting restricted stock units with various vesting periods ranging from one to four years years issued to certain employees and (iv) 604,000 were market performance-based cliff vesting restricted stock units with a three-year vesting period issued to certain employees.

Of the restricted stock units granted for the year ended December 31, 2017, (i) 18,348 were time-based graded vesting restricted stock units with a two-year and a three-year vesting period issued to non-employee trustees as part of their annual compensation, (ii) 69,860 were time-based graded vesting restricted stock units with a five-year vesting period issued to certain employees a (iii) 71,428 were performance-based cliff vesting restricted stock units with a five-year vesting period based upon achievement of annual Company EBITDA performance against target.



Year Ended December 31, 2019
Restricted Stock	Number of Time-Based Restricted Stock Units		Aggregate Intrinsic Value (in millions)		Number of Performance-Based Restricted Stock Units		Aggregate Intrinsic Value (in millions)		Number of Market Performance-Based Restricted Stock Units		Aggregate Intrinsic Value (in millions)
Non-vested as of December 31, 2018	1,028,256		$	26.3	71,428		$	1.8	587,500		$	15.0
Granted	280,083				—				243,168
Vested⁽¹⁾	(443,481	)			(14,286	)			—
Forfeited	(150,795	)			—				(51,480	)
Non-vested as of December 31, 2019	714,063		$	25.0	57,142		$	2.0	779,188		$	27.3
Shares vested, but not released⁽¹⁾	615,643		21.6		14,286		0.5		—		—
Total outstanding restricted stock units	1,329,706		$	46.6	71,428		$	2.5	779,188		$	27.3

The weighted average grant date fair value of restricted stock units granted during years 2019, 2018, and 2017 was $33.29, $17.21 and $13.13 per unit, respectively. During the year ended December 31, 2019 the weighted average grant date fair value of vested and converted restricted stock units was $17.34 and forfeited restricted stock units

During the year ended December 31, 2019, the Compensation Committee of the Board of Trustees approved the annual grant of market performance-based restricted stock units under the 2017 Plan to employees of the Company. The awards utilize relative total shareholder return (TSR) over a three-year measurement period as the market performance metric. Awards will vest based on the Company’s TSR relative to the RMZ over a three-year market performance period, or the Market Performance Period, commencing in January 1, 2019 and ending on December 31, 2021, as applicable (or, if earlier, ending on the date on which a change in control of the Company occurs), subject to continued services. Vesting with respect to the market condition is measured based on the difference between the Company’s TSR percentage and the TSR percentage of the RMZ, or the RMZ Relative Market Performance. In the event that the RMZ Relative Market Performance during the Market Performance Period is achieved at the “threshold,” “target” or “high” level as set forth below, the awards will become vested as to the market condition with respect to the percentage of RSUs, as applicable, set forth below:

Market performance-based restricted units granted during 2018 utilize absolute total shareholder return (TSR) over a three-year measurement period as the market performance metric. Awards will vest based on the Company’s TSR relative to the percentage appreciation (rounded to the nearest tenth of a percent), in the value per share of stock during the performance period, over a three-year market performance period, commencing on January 18, 2018 and ending on December 31, 2020 (or, if earlier, ending on the date on which a change in control of the Company occurs), subject to continued services. In the event that the TSR upon completion of the market performance period is achieved at the “minimum,” “target” or “maximum” level as set forth below, the awards will become vested as to the market condition with respect to the percentage RSUs, as applicable, set forth below:

In the event that the Company’s TSR does not meet 50% of the Target Award (i.e., the minimum threshold listed above), the Restricted Stock Units shall be automatically forfeited and neither the Company nor any Subsidiary shall have any further obligations to the participant under the agreement. In no event will the number of RSUs that vest pursuant to the agreement exceed 150% of the Target Award.

The fair values of the awards were measured using a Monte Carlo simulation to estimate the probability of the market vesting condition being satisfied. The Company’s achievement of the market vesting condition is contingent on its TSR over a three-year market performance period, relative to the total stock price. Monte Carlo simulation is well-accepted for pricing market based awards, where the number of shares that will vest depends on the future stock price movements. For each simulated path, the TSR is calculated at the end of the performance period and determines the vesting percentage based on achievement of the performance target. The fair value of the RSUs is the average discounted payout across all simulation paths. Assumptions used in the valuations are summarized as follows:

The grant of the performance-based restricted stock unit award in April 2017 resulted in a grant date fair value of $13.43 and was measured utilizing the Black-Scholes methodology. The Company’s achievement of the performance vesting condition was contingent on the achievement of Core EBITDA. The key assumptions used in the valuation of the April 2017 award were as follows:

During the year ended December 31, 2019, upon recommendation by the Compensation Committee, the Board of Trustees approved the grant of OP units in connection with future grants made to the Board of Trustees and management of the Company at the Senior Vice President level or above. The recipient will have the option to elect their grant in the form of either restricted stock units or OP units. As a result of this election, a total of 20,190 time-based OP Units were granted to certain trustees as part of their annual compensation. The OP units will vest in one year, had an aggregate grant date fair value of $0.7 million, and had an aggregate intrinsic value of $0.7 million as of December 31, 2019. During the year ended December 31, 2019, there were no OP units granted to management of the Company.



	Number of Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Terms (Years)
Outstanding as of December 31, 2018	2,355,787		$	9.81	5.4
Granted	—		—
Exercised	(1,342,289	)	9.81
Forfeited or expired	(219,000	)	9.81
Outstanding as of December 31, 2019	794,498		$	9.81	5.8

Exercisable as of December 31, 2019	301,500		$	9.81	5.1