Common Stock and Stock-Based Compensation (Tables)

12 Months Ended

May 31, 2016

The following table summarizes the Company’s total stock-based compensation expense recognized in Operating overhead expense:



	Year Ended May 31,
(In millions)	2016		2015		2014
Stock options⁽¹⁾	$	171	$	136	$	125
ESPPs	31		24		22
Restricted stock	34		31		30
TOTAL STOCK-BASED COMPENSATION EXPENSE	$	236	$	191	$	177


(1)	Expense for stock options includes the expense associated with stock appreciation rights. Accelerated stock option expense is recorded for employees eligible for accelerated stock option vesting upon retirement. Accelerated stock option expense for the years ended May 31, 2016, 2015 and 2014 was $30 million, $19 million and $15 million, respectively.

The weighted average assumptions used to estimate these fair values are as follows:



	Year Ended May 31,
	2016		2015		2014
Dividend yield	1.0	%	1.2	%	1.3	%
Expected volatility	23.6	%	23.6	%	27.9	%
Weighted average expected life (in years)	5.8		5.8		5.3
Risk-free interest rate	1.7	%	1.7	%	1.3	%

The following summarizes the stock option transactions under the plan discussed above:



	Shares⁽¹⁾		Weighted Average Option Price
	(In millions)
Options outstanding May 31, 2013	135.3		$	17.36
Exercised	(22.0	)	14.15
Forfeited	(2.5	)	24.17
Granted	16.3		31.77
Options outstanding May 31, 2014	127.1		19.64
Exercised	(27.2	)	15.39
Forfeited	(2.1	)	29.51
Granted	18.4		38.84
Options outstanding May 31, 2015	116.2		23.50
Exercised	(22.5	)	17.75
Forfeited	(2.3	)	39.96
Granted	20.6		56.41
Options outstanding May 31, 2016	112.0		$	30.38
Options exercisable at May 31,
2014	74.0		$	15.71
2015	68.6		18.26
2016	66.5		21.48


(1)	Includes stock appreciation rights transactions.