10. Share-Based Compensation

On April 10, 2018, the Company adopted the Tutor Perini Corporation Omnibus Incentive Plan (the “Current Plan”), which was approved by the Company’s shareholders on May 23, 2018. The Current Plan effected the merger of the Company’s Amended and Restated Tutor Perini Corporation Long-Term Incentive Plan, as amended and restated on October 2, 2014 (the “2014 Plan”) and the Tutor Perini Corporation Incentive Compensation Plan adopted on April 3, 2017 (the “2017 Plan,” together with the 2014 Plan and the Current Plan, the “Plans”). The Current Plan provides for various types of share-based grants, including restricted and unrestricted stock units and stock options. Restricted and unrestricted stock units give the holder the right to exchange their stock units for shares of the Company’s common stock on a one-for-one basis. Stock options give the holder the right to purchase shares of the Company’s common stock subsequent to the vesting date at a defined exercise price. A stock option exercise price must be equal to or greater than the fair value of the Company’s common stock on the date of the award. Restricted stock units and stock options are usually subject to certain service and performance conditions as well as other restrictions. The term for stock options is limited to 10 years from the date of grant. As of December 31, 2018, there were 800,667 shares of common stock available for grant under the Company’s Current Plan. As of December 31, 2018, the Plans had an aggregate of 4,732,044 of restricted stock units and stock options from outstanding, historical awards that either have not vested or have vested but have not been exercised. Any awards that were granted under the 2014 Plan or the 2017 Plan that are forfeited, cancelled or held back for net settlement will become available to be issued under the Current Plan.

The terms of the Plans give the Company the right to settle the vesting of share-based grants in cash or shares. During the year ended December 31, 2018, the Company did not settle any awards in cash. During the year ended December 31, 2017, the Company paid approximately $0.6 million to settle share-based awards.

Many of the awards issued under the Plans contain separate tranches, each for a separate performance period and each with a performance target to be established subsequent to the award date; accordingly, the tranches are accounted for under ASC 718, Stock Compensation (“ASC 718”) as separate grants, with the grant date being the date the performance targets for a given tranche are established and communicated to the grantee. Similarly, for these awards, compliance with the requirements of the Plans is also based on the number of units granted in a given year, as determined by ASC 718, rather than the number of units awarded in a given year. As a result, as of December 31, 2018, the Company had outstanding awards with 160,000 restricted stock units and 160,000 stock options that had not been granted yet. These units will be granted in 2019 and 2020 when the performance targets for those respective years are established.

The following table summarizes restricted stock unit and stock option activity:



	Restricted Stock Units			Stock Options
		Weighted-			Weighted-
		Average			Average
		Grant Date			Exercise/
		Fair Value			(Strike) Price
	Number	Per Share		Number	Per Share
Outstanding as of December 31, 2015	725,597	$	25.28	1,998,000	$	19.62
Granted	483,387		19.14	274,000		16.20
Vested/exercised	(52,500)		18.74	(97,500)		12.72
Outstanding as of December 31, 2016	1,156,484	$	22.64	2,174,500	$	19.50
Granted	1,064,000		30.02	539,000		24.54
Expired or cancelled	(20,985)		23.91	(19,466)		26.56
Vested/exercised	(801,515)		19.38	(140,000)		21.41
Outstanding as of December 31, 2017	1,397,984	$	30.11	2,554,034	$	20.45
Granted	699,000		24.21	664,000		23.20
Expired or cancelled	(240,289)		32.76	(274,990)		22.82
Vested/exercised	(387,695)		28.67	—		—
Outstanding as of December 31, 2018	1,469,000	$	27.27	2,943,044	$	20.89

The following table summarizes unrestricted stock units, which are generally issued to the non-employee members of the Company’s Board of Directors as part of their annual retainer fees:



	Unrestricted Stock Units
		Weighted-Average
		Grant Date
Year	Number	Fair Value Per Share
2016	64,603	$	21.67
2017	99,155		26.26
2018	115,420		21.26

The fair value of unrestricted stock units issued during 2018, 2017 and 2016 was approximately $2.5 million, $2.6 million and $1.4 million, respectively.

The fair value of restricted stock units that vested during 2018, 2017 and 2016 was approximately $7.9 million, $25.3 million and $1.0 million, respectively. There were no stock options exercised during 2018. The aggregate intrinsic value, representing the difference between the market value on the date of exercise and the option price of the stock options exercised during 2017 and 2016 was $1.3 million and $1.1 million, respectively, with a corresponding tax benefit of $0.6 million and $0.5 million, respectively. As of December 31, 2018, the balance of unamortized restricted stock and stock option expense was $21.4 million and $6.0 million, respectively, which will be recognized over weighted-average periods of 2.0 years for both restricted stock units and stock options.

The 2,943,044 outstanding stock options as of December 31, 2018 had an intrinsic value of $2.5 million and a weighted-average remaining contractual life of 4.8 years. Of those outstanding options: (1) 2,034,044 were exercisable with an intrinsic value of $2.5 million, a weighted-average exercise price of $19.42 per share and a weighted-average remaining contractual life of 3.1 years; (2) 909,000 have been granted but have not vested with no intrinsic value, a weighted-average exercise price of $23.92 per share and a weighted-average remaining contractual life of 8.5 years. Of the granted but unvested options, 876,750, are expected to vest.

The fair value of restricted and unrestricted stock units is based on the closing price of the Company’s common stock on the New York Stock Exchange on the date of the grant and the fair value of stock options is based on the Black-Scholes model. For certain performance-based awards containing market condition components, the fair value on the grant date is determined using a Monte Carlo simulation model.

The fair value on the grant date and the significant assumptions used in the Black-Scholes option-pricing model are as follows:



	Year Ended December 31,
	2018			2017			2016
Total stock options granted		664,000			539,000			274,000
Weighted-average grant date fair value	$	11.09		$	13.11		$	5.31
Weighted-average assumptions:
Risk-free rate		2.6	%		1.8	%		1.2	%
Expected life of options(a)		5.8			4.8			4.2
Expected volatility(b)		42.2	%		43.1	%		40.6	%
Expected quarterly dividends	$	—		$	—		$	—

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(a)

Calculated using the simplified method due to the terms of the stock options and the limited pool of grantees.

(b)

Calculated using historical volatility of the Company’s common stock over periods commensurate with the expected life of the option.

For the respective years ended December 31, 2018, 2017 and 2016, the Company recognized, as part of general and administrative expenses, costs for share-based payment arrangements for employees of $21.1 million, $19.6 million and $13.4 million. Additionally for the same periods, the Company also recognized as part of general and administrative expenses costs for share-based awards to non-employee directors of $1.7 million, $1.6 million and $1.4 million, respectively. The aggregate tax benefits for these awards were approximately $3.8 million, $8.7 million and $6.1 million, for the respective periods.