During the nine months ended September 30, 2021, we granted to certain employees 498,955 LTIP Units with time-based vesting requirements ("Time-Based LTIP Units") with a weighted average grant-date fair value of $29.21 per unit that

primarily vest ratably over four years subject to continued employment. Compensation expense for these units is being recognized over a four-year period.

Additionally, in January 2021, we granted 163,065 fully vested LTIP Units to certain employees, who elected to receive all or a portion of their cash bonus, related to 2020 service, as LTIP Units. The LTIP units had a grant-date fair value of $29.54 per unit. Compensation expense totaling $4.8 million for these LTIP Units was recognized in 2020.

In April 2021, as part of their annual compensation, we granted to non-employee trustees a total of 71,792 fully vested LTIP Units with an aggregate grant-date fair value of $1.9 million. The LTIP Units may not be sold while a trustee is serving on the Board of Trustees.

In July 2021, we granted to certain employees 608,325 Time-Based LTIP Units with a weighted average grant-date fair value of $31.73 per unit that vest 50% on the fifth anniversary of the grant date and 25% on each of the sixth and seventh anniversaries of the grant date, subject to continued employment. Compensation expense for these units is being recognized over a seven-year period.

The aggregate grant-date fair value of the Time-Based LTIP Units and LTIP Units granted during the nine months ended September 30, 2021 was $40.6 million. The Time-Based LTIP Units and LTIP Units were valued based on the closing common share price on the date of grant, less a discount for post-grant restrictions. The discount was determined using Monte Carlo simulations, and the following is a summary of the significant assumptions used to value these units:

In January 2021, we granted to certain employees 627,874 LTIP Units with performance-based vesting requirements ("Performance-Based LTIP Units") with a weighted average grant-date fair value of $15.14 per unit. Our Performance-Based LTIP Units have a three-year performance period. 50% of any Performance-Based LTIP Units that are earned vest at the end of the three-year performance period and the remaining 50% vest on the fourth anniversary of the date of grant, subject to continued employment. If, however, the Performance-Based LTIP Units do not achieve a positive absolute total shareholder return ("TSR") at the end of the three-year performance period, but satisfy the relative performance criteria thereof, 50% of the units that otherwise could have been earned will be forfeited, and the remaining units that are earned will vest if and when we achieve a positive TSR during the succeeding seven years, measured at the end of each quarter. Compensation expense for these units is generally being recognized over a four-year period. In January 2021, the three-year performance period ended for the Performance-Based LTIP Units granted on February 2, 2018. Based on our relative performance and absolute TSR over the three-year performance period, 100% of the units granted were earned.

In July 2021, we granted to certain employees 844,070 Performance-Based LTIP Units with a weighted average grant-date fair value of $23.08 per unit that vest 50% on the fifth anniversary of the grant date and 25% on each of the sixth and seventh anniversaries of the grant date, subject to continued employment, and earn based on our achievement of four share price targets during the performance period commencing on the first anniversary of the grant date and ending on the sixth anniversary of the grant date. Compensation expense for these units is being recognized over a seven-year period.

The aggregate grant-date fair value of the Performance-Based LTIP Units granted during the nine months ended September 30, 2021 was $29.0 million, valued using Monte Carlo simulations. The following is a summary of the significant assumptions used to value the Performance-Based LTIP Units:

In January 2021, we granted to certain non-executive employees 22,194 RSUs with time-based vesting requirements ("Time-Based RSUs") with a weighted average grant-date fair value of $31.52 per unit and 13,516 RSUs with performance-based vesting requirements ("Performance-Based RSUs") with a weighted average grant-date fair value of $15.16 per unit. Vesting requirements and compensation expense recognition for the Time-Based RSUs and the Performance-Based RSUs are identical to those of the Time-Based LTIP Units and Performance-Based LTIP Units granted in January 2021.

The aggregate grant-date fair value of the RSUs granted during the nine months ended September 30, 2021 was $905,000. The Time-Based RSUs were valued based on the closing common share price on the date of grant and the Performance-Based RSUs were valued using Monte Carlo simulations with the same significant assumptions used to value the Performance-Based LTIP Units above.

Pursuant to the ESPP, employees purchased 34,320 common shares for $880,000 during the nine months ended September 30, 2021. The following is a summary of the significant assumptions used to value the ESPP common shares using the Black-Scholes model:

(1)	Primarily comprising compensation expense for: (i) fully vested LTIP Units issued to certain employees in lieu of all or a portion of any cash bonus earned, (ii) RSUs and (iii) shares issued under our ESPP.

(2)	Represents share-based compensation expense for LTIP Units and OP Units issued in the Formation Transaction, which are subject to post-Combination employment obligations.

(3)	Represents equity awards issued related to our successful pursuit of Amazon's additional headquarters in National Landing.

(4)	Included in "General and administrative expense: Share-based compensation related to Formation Transaction and special equity awards" in the accompanying statements of operations.

As of September 30, 2021, we had $73.7 million of total unrecognized compensation expense related to unvested share-based payment arrangements, which is expected to be recognized over a weighted average period of 3.5 years.