Stock Plans

9 Months Ended

Feb. 28, 2021

Stock Plans [Abstract]

Stock Plans

(9) Stock Plans

We have various stock-based compensation programs under which awards, including stock options, restricted stock, restricted stock units, and performance awards, may be granted to employees and non-employee directors. These programs and related accounting are described in Note 12 to the Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended May 31, 2020.

Compensation expense related to stock-based payments recognized in the Consolidated Statements of Earnings was as follows:

	Quarter Ended				Nine-Month Period Ended
In Millions	Feb. 28, 2021			Feb. 23, 2020	Feb. 28, 2021		Feb. 23, 2020
Compensation expense related to stock-based payments	$	20.8	$	18.2	$	69.5	$	66.0

Windfall tax benefits from stock-based payments in income tax expense in our Consolidated Statements of Earnings were as follows:

	Quarter Ended				Nine-Month Period Ended
In Millions	Feb. 28, 2021		Feb. 23, 2020		Feb. 28, 2021		Feb. 23, 2020
Windfall tax benefits from stock-based payments	$	1.6	$	4.1	$	8.4	$	12.3

As of February 28, 2021, unrecognized compensation expense related to non-vested stock options, restricted stock units, and performance share units was $123.2 million. This expense will be recognized over 21 months, on average.

Net cash proceeds from the exercise of stock options less shares used for withholding taxes and the intrinsic value of options exercised were as follows:

	Nine-Month Period Ended
In Millions	Feb. 28, 2021		Feb. 23, 2020
Net cash proceeds	$	39.4	$	109.4
Intrinsic value of options exercised	$	24.2	$	54.0

We estimate the fair value of each stock option on the grant date using a Black-Scholes option-pricing model. Black-Scholes option-pricing models require us to make predictive assumptions regarding future stock price volatility, employee exercise behavior, and dividend yield. We estimate our future stock price volatility using the historical volatility over the expected term of the option, excluding time periods of volatility we believe a marketplace participant would exclude in estimating our stock price volatility. We also have considered, but did not use, implied volatility in our estimate, because trading activity in options on our stock, especially those with tenors of greater than 6 months, is insufficient to provide a reliable measure of expected volatility. Our method of selecting the other valuation assumptions is explained in Note 12 to the Consolidated Financial Statements included in our Annual Report on Form 10-K for the fiscal year ended May 31, 2020.

The estimated fair values of stock options granted and the assumptions used for the Black-Scholes option-pricing model were as follows:

	Nine-Month Period Ended
	Feb. 28, 2021			Feb. 23, 2020
Estimated fair values of stock options granted	$	8.03		$	7.10
Assumptions:
Risk-free interest rate		0.7	%		2.0	%
Expected term		8.5	years		8.5	years
Expected volatility		19.5	%		17.4	%
Dividend yield		3.3	%		3.6	%

The total grant date fair value of restricted stock unit awards that vested during the period follows:

	Nine-Month Period Ended
In Millions		Feb. 28, 2021		Feb. 23, 2020
Total grant date fair value	$	73.0	$	57.1