We recognized total stock-based compensation expense as follows:



	Year Ended December 31,
(millions)	2019			2018			2017
General and Administrative Expense	$	59		$	54		$	56
Exploration Expense and Other	9			8			48
Total Stock-Based Compensation Expense⁽¹⁾	$	68		$	62		$	104
Tax Benefit Recognized	$	(14	)	$	(13	)	$	(36	)

2017 Long-Term Incentive Plan On April 25, 2017, our shareholders approved the Noble Energy, Inc. 2017 Long-Term Incentive Plan (the 2017 Plan). Upon shareholder approval, the 2017 Plan superseded and replaced the Noble Energy, Inc. 1992 Stock Option and Restricted Stock Plan, as amended (the 1992 Plan) which was frozen so that no future grants would be made under the 1992 Plan. The 1992 Plan continues to govern awards that were outstanding as of the date of its suspension, which remain in effect pursuant to their terms. Under the 2017 Plan, the Compensation, Benefits and Stock Option Committee of the Board of Directors (the Committee) may grant stock options, stock appreciation rights, restricted stock, restricted stock units, performance awards, stock awards and other incentive awards to our officers or other employees and those of our subsidiaries. The maximum number of shares that may be granted under the 2017 Plan is 44 million shares of common stock. At December 31, 2019, 39,693,735 shares of our common stock were reserved for issuance, including 28,407,839 shares available for future grants and awards, under the 2017 Plan.

Stock options are issued with an exercise price equal to the fair market value of our common stock on the date of grant, and are subject to such other terms and conditions as may be determined by the Committee. Unless granted by the Committee for a shorter term, the options expire 10 years from the grant date. Option grants generally vest ratably over a three-year period.

Restricted stock awards made under the 2017 Plan are subject to such restrictions, terms and conditions, including forfeitures, if any, as may be determined by the Committee. During the period in which such restrictions apply, unless specifically provided otherwise in accordance with the terms of the 2017 Plan, the recipient of restricted stock would be the record owner of the shares and have all the rights of a shareholder with respect to the shares, including the right to vote and the right to receive dividends or other distributions made or paid with respect to the shares. The dividends or other distributions pertaining to the restricted shares will be held by the Company until the restriction period ends and the shares vest or forfeit. If the restricted shares forfeit, then the recipient shall not be entitled to receive the dividend or distribution, which will transfer to the Company. Restricted stock awards with a time-vested restriction vest over a two or three-year period. Performance share awards cliff vest after a three-year period if the Company achieves certain levels of total shareholder return relative to a pre-determined industry peer group.

2015 Stock Plan for Non-Employee Directors The 2015 Stock Plan for Non-Employee Directors of Noble Energy, Inc., as amended (the 2015 Plan) provides for grants of stock options and awards of restricted stock to our non-employee directors. The 2015 Plan superseded and replaced the 2005 Stock Plan for Non-Employee Directors of Noble Energy, Inc. The total number of shares of our common stock that may be issued under the 2015 Plan is 708,996. At December 31, 2019, 485,062 shares of our common stock were reserved for issuance, including 306,243 shares available for future grants and awards, under the 2015 Plan.

The assumptions used in valuing stock options granted were as follows:



	Year Ended December 31,
(weighted averages)	2019			2018			2017
Expected Term (in Years)	6.9			6.7			6.4
Expected Volatility	33.8		%	33.4		%	33.2		%
Risk-Free Rate	2.7		%	2.6		%	2.2		%
Expected Dividend Yield	1.4		%	1.2		%	0.9		%
Weighted Average Grant-Date Fair Value	$	7.57		$	10.47		$	13.26

Stock option activity was as follows:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
			(per share)		(years)	(millions)
Outstanding at December 31, 2018	13,852,020		$	44.04
Granted	461,311		22.15
Forfeited	(51,100	)	34.72
Expired	(1,686,478	)	35.26
Outstanding at December 31, 2019	12,575,753		$	44.62	4.2	$	1
Exercisable at December 31, 2019	11,373,846		$	46.11	3.7	$	—

There were no options exercised in 2019. The total intrinsic value of options exercised was $5 million in 2018 and $4 million in 2017. As of December 31, 2019, $5 million of compensation cost related to unvested stock options granted under the Plans remained to be recognized. The cost is expected to be recognized over a weighted-average period of 1.2 years. We issue new shares of our common stock to settle option exercises. Dividends are not paid on unexercised options.

Restricted Stock Awards Awards of time-vested restricted stock (shares subject to service conditions) are valued at the price of our common stock at the date of award. The fair value of the market based restricted stock awards was estimated on the date of award using a Monte Carlo valuation model that uses the assumptions in the following table. The Monte Carlo valuation model is based on random projections of stock price paths and must be repeated numerous times to achieve a probabilistic assessment. Expected volatility represents the extent to which our stock price is expected to fluctuate between now and the award’s anticipated term. We use the historical volatility of Noble Energy common stock for the three-year period ended prior to the date of award. The risk-free rate is based on a three-year period for US Treasury securities as of the year ended prior to the date of award.

The assumptions used in valuing market based restricted stock awards granted were as follows:



	Year Ended December 31,
	2019		2018		2017
Number of Simulations	10,000,000		10,000,000		500,000
Expected Volatility	37.5	%	35.0	%	35.0	%
Risk-Free Rate	2.5	%	2.3	%	1.5	%

Restricted stock activity was as follows:



	Subject to Time Vesting				Subject to Market Conditions
	Number of Shares		Weighted Average Award Date Fair Value		Number of Shares		Weighted Average Award Date Fair Value
			(per share)				(per share)
Outstanding at December 31, 2018	3,172,891		$	32.72	1,385,634		$	21.74
Awarded	2,464,682		22.33		1,138,730		13.50
Vested	(906,485	)	34.11		—		—
Forfeited	(486,733	)	27.97		(347,948	)	21.20
Outstanding at December 31, 2019	4,244,355		$	27.02	2,176,416		$	17.52

The total fair value of restricted stock that vested was $20 million in 2019, $29 million in 2018, and $34 million in 2017. The weighted average award-date fair value per share of restricted stock awarded was $19.54 in 2019, $27.96 in 2018, and $35.45 in 2017.

As of December 31, 2019, $74 million of compensation cost related to all of our unvested restricted stock awarded under the Plans remained to be recognized. The cost is expected to be recognized over a weighted-average period of 1.4 years. Common stock dividends accrue on restricted stock awards and are paid upon vesting. We issue new shares of our common stock when awarding restricted stock.

Cash-Settled Awards Periodically, we issue cash-settled awards (so called phantom units, the nomenclature used in accounting literature) to certain employees in lieu of a portion of restricted stock and stock options. These phantom units represented a hypothetical interest in the Company and, once vested, are settled in cash. Common stock dividends accrue on phantom units and are paid upon vesting.

On February 1, 2016, we issued one million phantom units under the 1992 Plan, a portion of which were subject to the Company's achievement of certain levels of total shareholder return relative to a pre-determined industry peer group. The phantom units vested during 2019 at $31.65 per share which was equal to the grant date fair value. The fair value of the market based phantom unit awards was estimated on the date of award using a Monte Carlo valuation model and assumed 500,000 simulations, 38% expected volatility and a risk-free rate of 0.9%. These awards vested at 0% as performance was not achieved.

On February 19, 2019, we issued 803,606 phantom units under the 2017 Plan. The units had a grant date fair value of $22.39 and vest ratably over three years. The value at vesting will equal the fair market value of a share of common stock of the Company as of the vesting date.

Phantom unit activity was as follows:



	Subject to Time Vesting				Subject to Market Conditions
	Number of Units		Weighted Average Award Date Fair Value		Number of Units		Weighted Average Award Date Fair Value
			(per share)				(per share)
Outstanding at December 31, 2018	467,365		$	31.65	150,296		$	6.82
Awarded	803,606		22.39		—		—
Vested	(462,823	)	31.65		—		—
Forfeited	(92,762	)	22.55		(150,296	)	6.82
Outstanding at December 31, 2019	715,386		$	22.39	—		$	—

As of December 31, 2019, $11 million of compensation cost related to phantom units remained to be recognized. The cost is expected to be recognized over a weighted-average period of 2.1 years. The total fair value of phantom units that vested in 2019 was $10 million. We accrued a liability of $5 million in 2019 related to the phantom units.

401(k) Plan We sponsor a 401(k) savings plan. All regular employees are eligible to participate. We make contributions to match employee contributions up to the first 6% of compensation deferred into the plan, and certain profit sharing contributions for employees hired on or after May 1, 2006, based upon their ages and salaries. We made cash contributions of $32 million in 2019, $31 million in 2018 and $31 million in 2017.

Deferred Compensation Plans We have a non-qualified deferred compensation plan for which participant-directed investments are held in a rabbi trust and are available to satisfy the claims of our creditors in the event of bankruptcy or insolvency. Participants may elect to receive distributions in either cash or shares of our common stock. Assets within the rabbi trust primarily consist of mutual fund investments, which include various publicly-traded mutual funds that, in turn, include investments ranging from equities to money market instruments and totaled $27 million at December 31, 2019. The fair values are based on quoted market prices for identical assets.

The liability associated with the deferred compensation plan, which is dependent upon the fair values of the mutual fund investments and common stock held in the rabbi trust, was $29 million and $43 million at December 31, 2019 and 2018, respectively. The rabbi trust included 64,729 and 267,792 shares of our common stock at December 31, 2019 and 2018, respectively, which are accounted for as treasury stock. Distributions of 200,000 shares were made in each of 2019, 2018 and 2017 and were valued at $23 million in 2019, $18 million in 2018 and $21 million in 2017.

We also maintain other nonqualified deferred compensation plans for the benefit of certain of our employees. Deferred compensation liabilities under these plans were $99 million and $104 million at December 31, 2019 and 2018, respectively.