Share Plans

3 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

Total share-based compensation expense for the three months ended March 31, 2021 and 2020 was as follows:


	Three months ended
In millions		March 31, 2021		March 31, 2020
Restricted stock units		$	3.4	$	3.2
Stock options		0.9		1.0
Performance share units		1.3		2.0
Total share-based compensation expense		$	5.6	$	6.2

In the first quarter of 2021, we issued our annual share-based compensation grants under the Pentair plc 2020 Share and Incentive Plan to eligible employees. The total number of awards issued was approximately 0.7 million, of which 0.3 million were restricted stock units (“RSUs”), 0.3 million were stock options and 0.1 million were performance share units (“PSUs”). The weighted-average grant date fair value of the RSUs, stock options and PSUs issued was $55.42, $12.88, and $52.57, respectively.

We estimated the fair value of each stock option award issued in the annual share-based compensation grant using a Black-Scholes option pricing model, modified for dividends and using the following assumptions:


	2021 Annual Grant
Risk-free interest rate	0.37	%
Expected dividend yield	1.56	%
Expected share price volatility	29.60	%
Expected term (years)	6.5

These estimates require us to make assumptions based on historical results, observance of trends in our share price, changes in option exercise behavior, future expectations and other relevant factors. If other assumptions had been used, share-based compensation expense, as calculated and recorded under the accounting guidance, could have been affected. We based the expected life assumption on historical experience as well as the terms and vesting periods of the options granted. For purposes of determining expected share price volatility, we considered a rolling average of historical volatility measured over a period approximately equal to the expected option term. The risk-free interest rate for periods that coincide with the expected life of the options is based on the United States (“U.S.”) Treasury Department yield curve in effect at the time of grant.