Share Plans

Total share-based compensation expense for the three months ended March 28, 2015 and March 29, 2014 was as follows:



	Three months ended
In millions	March 28, 2015		March 29, 2014
Restricted stock units	$	6.2	$	4.9
Stock options	3.5		2.5
Total share-based compensation expense	$	9.7	$	7.4

In the first quarter of 2015, we issued our annual share-based compensation grants under the Pentair plc 2012 Stock and Incentive Plan to eligible employees. The total number of awards issued was approximately 0.8 million, of which 0.6 million were stock options and 0.2 million were restricted stock units. The weighted-average grant date fair value of the stock options and restricted stock units issued was $16.73 and $66.44, 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:



	2015 Annual Grant
Risk-free interest rate	1.61	%
Expected dividend yield	1.96	%
Expected share price volatility	30.4	%
Expected term (years)	6.0

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 U.S. Treasury Department yield curve in effect at the time of grant.