Stock-Based Compensation

We issue stock-based incentive awards to our eligible employees and Directors under the 2002 Employee Stock Incentive Plan and a Director Deferred Stock Ownership Plan.

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2002 Employee Stock Incentive Plan (the “2002 Plan”) – The 2002 Plan permits the granting of nonqualified stock options, stock appreciation rights, performance stock, restricted stock and other stock-based awards. In 2018, we made a one-time issuance of incentive stock options under the 2002 Plan to replace Kensho employees' stock options that were assumed in connection with our acquisition of Kensho in April of 2018.

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Director Deferred Stock Ownership Plan – Under this plan, common stock reserved may be credited to deferred stock accounts for eligible Directors. In general, the plan requires that 50% of eligible Directors’ annual compensation plus dividend equivalents be credited to deferred stock accounts. Each Director may also elect to defer all or a portion of the remaining compensation and have an equivalent number of shares credited to the deferred stock account. Recipients under this plan are not required to provide consideration to us other than rendering service. Shares will be delivered as of the date a recipient ceases to be a member of the Board of Directors or within five years thereafter, if so elected. The plan will remain in effect until terminated by the Board of Directors or until no shares of stock remain available under the plan.

The number of common shares reserved for issuance are as follows:



(in millions)	December 31,
	2018	2017
Shares available for granting under the 2002 Plan	33.3	33.8
Options outstanding	1.7	2.1
Total shares reserved for issuance ¹	35.0	35.9


¹	Shares reserved for issuance under the Director Deferred Stock Ownership Plan are not included in the total, but are less than 0.1 million.

We issue treasury shares upon exercise of stock options and the issuance of restricted stock and unit awards. To offset the dilutive effect of the exercise of employee stock options, we periodically repurchase shares. See Note 9 – Equity for further discussion.

Stock-based compensation expense and the corresponding tax benefit are as follows:



(in millions)	Year Ended December 31,
	2018		2017		2016
Stock option expense	$	5	$	3	$	7
Restricted stock and unit awards expense	89		96		69
Total stock-based compensation expense	$	94	$	99	$	76

Tax benefit	$	19	$	38	$	29

Stock Options

Stock options may not be granted at a price less than the fair market value of our common stock on the date of grant. Stock options granted vest over a four year service period and have a maximum term of 10 years. Stock option compensation costs are recognized from the date of grant, utilizing a four-year graded vesting method. Under this method, more than half of the costs are recognized over the first twelve months, approximately one-quarter of the costs are recognized over a twenty-four month period starting from the date of grant, approximately one-tenth of the costs are recognized over a thirty-six month period starting from the date of grant, and the remaining costs recognized over a forty-eight month period starting from the date of grant.

We use a lattice-based option-pricing model to estimate the fair value of options granted. The following assumptions were used in valuing the options granted:



	Year Ended
	December 31, 2018
Risk-free average interest rate	2.6 - 2.7%
Dividend yield	1.1		%
Volatility	21.8 - 22.0%
Expected life (years)	5.67 - 6.07
Weighted-average grant-date fair value per option	$	112.98

Because lattice-based option-pricing models incorporate ranges of assumptions, those ranges are disclosed. These assumptions are based on multiple factors, including historical exercise patterns, post-vesting termination rates, expected future exercise patterns and the expected volatility of our stock price. The risk-free interest rate is the imputed forward rate based on the U.S. Treasury yield at the date of grant. We use the historical volatility of our stock price over the expected term of the options to estimate the expected volatility. The expected term of options granted is derived from the output of the lattice model and represents the period of time that options granted are expected to be outstanding.

In 2018, we made a one-time issuance of incentive stock options under the 2002 Plan to replace Kensho employees' stock options that were assumed in connection with our acquisition of Kensho in April of 2018. There were no stock options granted in 2017 and 2016.

Stock option activity is as follows:



(in millions, except per award amounts)	Shares		Weighted average exercise price		Weighted-average remaining years of contractual term	Aggregate intrinsic value
Options outstanding as of December 31, 2017	2.1		$	44.09
Granted	0.2		$	74.11
Exercised	(0.6	)	$	161.14
Forfeited and expired ¹	—		$	71.68
Options outstanding as of December 31, 2018	1.7		$	47.92	3.3	$	202
Options exercisable as of December 31, 2018	1.6		$	46.69	3.1	$	195

¹ There are less 0.1 million shares forfeited and expired.



(in millions, except per award amounts)	Shares			Weighted-average grant-date fair value
Nonvested options outstanding as of December 31, 2017	—			$	27.52
Granted	0.2			$	112.98
Vested	(0.1		)	$	112.36
Forfeited ¹	—			$	112.14
Nonvested options outstanding as of December 31, 2018	0.1			$	113.02
Total unrecognized compensation expense related to nonvested options	$	2
Weighted-average years to be recognized over	2.0


¹	There are less than 0.1 million shares forfeited.

The total fair value of our stock options that vested during the years ended December 31, 2018, 2017 and 2016 was $5 million, $4 million and $7 million, respectively.

Information regarding our stock option exercises is as follows:



(in millions)	Year Ended December 31,
	2018		2017		2016
Net cash proceeds from the exercise of stock options	$	34	$	75	$	88
Total intrinsic value of stock option exercises	$	77	$	118	$	95
Income tax benefit realized from stock option exercises	$	27	$	64	$	41

Restricted Stock and Unit Awards

Restricted stock and unit awards (performance and non-performance) have been granted under the 2002 Plan. Performance unit awards will vest only if we achieve certain financial goals over the performance period. Restricted stock non-performance awards have various vesting periods (generally three years), with vesting beginning on the first anniversary of the awards. Recipients of restricted stock and unit awards are not required to provide consideration to us other than rendering service.

The stock-based compensation expense for restricted stock and unit awards is determined based on the market price of our stock at the grant date of the award applied to the total number of awards that are anticipated to fully vest. For performance unit awards, adjustments are made to expense dependent upon financial goals achieved.

Restricted stock and unit activity for performance and non-performance awards is as follows:



(in millions, except per award amounts)	Shares			Weighted-average grant-date fair value
Nonvested shares as of December 31, 2017	0.8			$	124.91
Granted	1.0			$	182.75
Vested	(0.9		)	$	167.13
Forfeited	(0.1		)	$	149.03
Nonvested shares as of December 31, 2018	0.8			$	172.24
Total unrecognized compensation expense related to nonvested awards	$	76
Weighted-average years to be recognized over	1.9



	Year Ended December 31,
	2018		2017		2016
Weighted-average grant-date fair value per award	$	182.75	$	147.12	$	93.01
Total fair value of restricted stock and unit awards vested	$	154	$	147	$	99
Tax benefit relating to restricted stock activity	$	32	$	36	$	26