
6.	STOCK-BASED COMPENSATION

The SAIP provides for the granting of various stock awards to eligible employees of JLL. Such awards have historically been solely RSUs and generally have vested in three years. In 2018, we issued PSUs for the first time to certain employees under the SAIP, a supplement to the continued issuance RSU awards. PSU awards generally vest in three years, subject to performance and market conditions as applicable.

There were approximately 1.3 million shares available for grant under the SAIP as of December 31, 2018. We also have a stock-based compensation plan for our UK-based employees, the SAYE plan, that allows for the purchase of stock at a 15% discount from the market price at the beginning of the plan's vesting periods.

Stock-based compensation expense is included within Compensation and benefits expense on the Consolidated Statements of Comprehensive Income. Stock-based compensation expense consisted of the following.



	Year Ended December 31,
($ in millions)	2018		2017	2016
Stock unit awards	$	25.6	23.8	25.5
SAYE	1.3		1.4	1.4
Total	$	26.9	25.2	26.9

Restricted Stock Units and Performance Stock Units

RSU and PSU activity is presented in the below table.



	Shares (in thousands)		Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Life (in years)
Unvested as of December 31, 2015	706.0		$	111.78
Granted	299.3		107.74
Vested	(203.6	)	96.37
Forfeited	(50.8	)	117.48
Unvested as of December 31, 2016	750.9		113.97		1.71
Granted	188.4		119.08
Vested	(186.5	)	99.23
Forfeited	(25.1	)	117.07
Unvested as of December 31, 2017	727.7		118.96		1.24
Granted	277.2		156.13
Vested	(292.5	)	125.01
Forfeited	(59.7	)	131.84
Unvested as of December 31, 2018	652.7		$	131.32	2.02

We determine the fair value of RSUs, subject only to service requirements, based on the closing market price of our common stock on the grant date. PSUs are subject to service requirements and one or more performance measures, including (i) performance conditions (e.g. achievement against earnings per share targets) and (ii) for certain awards, a market condition (e.g. total shareholder return performance against a peer group). We determine the fair value of PSUs based on the closing market price of our common stock on the grant date taking into consideration the likelihood of achieving each performance condition and the market condition valuation, as applicable, based on the output of Monte Carlo simulations. Less than 10% of the unvested awards as of December 31, 2018 contained a market condition, and approximately 10% of the grant date fair value of these awards was linked to the market condition. The portion of PSU awards with a market condition was not material. As of December 31, 2018, we had $36.6 million of unamortized deferred compensation related to unvested RSUs and PSUs, which we anticipate to be recognized over varying periods into 2022.

Shares vested during the years ended December 31, 2018, 2017 and 2016, had grant date fair values of $43.3 million, $18.5 million, and $19.6 million, respectively. The increase in 2018 reflects the additional PSUs awarded during the year. Shares granted during the years ended December 31, 2018, 2017 and 2016 had grant date fair values of $36.5 million, $22.4 million and $32.2 million, respectively.

Other Stock-Based Compensation Programs

As previously discussed, we also maintain the SAYE plan for our UK-based employees. There were approximately 260 thousand shares available for grant under the SAYE plan as of December 31, 2018.

Options activity under the SAYE plan is presented in the following table.



	Year Ended December 31,
(options in thousands)	2018		2017		2016
Options granted	—		85		—
Exercise price - options granted	$	—	$	90.97	$	—

Options exercised	19		28		20
Weighted average exercise price	$	142.96	$	121.70	$	70.37

The fair values of options granted under the SAYE plan are amortized over their respective vesting periods. There were approximately 97 thousand, 133 thousand, and 128 thousand options outstanding under the SAYE plan as of December 31, 2018, 2017 and 2016, respectively.