Stock-Based Compensation

The compensation costs related to stock-based awards were as follows:



(Dollars in thousands)	February 2, 2018		February 3, 2017
Stock option awards	$	1,175	$	1,392
Restricted stock units	1,005		576
Performance share awards	414		1,112
Unrestricted common stock awards	530		538
Total compensation cost for stock-based awards	$	3,124	$	3,618

During the first quarter of fiscal years 2018 and 2017, 8,388 and 11,412 shares, respectively, of fully vested unrestricted common stock awards were granted to certain members of the company's Board of Directors as a component of their compensation for their service on the board and are recorded in selling, general and administrative expense in the Condensed Consolidated Statements of Earnings.

Stock Option Awards

Under The Toro Company Amended and Restated 2010 Equity and Incentive Plan, as amended and restated (the “2010 plan”), stock options are granted with an exercise price equal to the closing price of the company’s common stock on the date of grant, as reported by the New York Stock Exchange. Options are generally granted to executive officers, other employees, and non-employee members of the company’s Board of Directors on an annual basis in the first quarter of the company’s fiscal year. Options generally vest one-third each year over a three-year period and have a ten-year term. Other options granted to certain employees vest in full on the three-year anniversary of the date of grant and have a ten-year term. Compensation expense equal to the grant date fair value is generally recognized for these awards over the vesting period. Stock options granted to executive officers and other employees are subject to accelerated expensing if the option holder meets the retirement definition set forth in the 2010 plan. In that case, the fair value of the options is expensed in the fiscal year of grant because generally the option holder must be employed after the last day of the fiscal year in which the stock options are granted in order for the options to continue to vest following retirement. Similarly, if a non-employee director has served on the company’s Board of Directors for ten full fiscal years or more, the awards vest immediately upon retirement, and therefore, the fair value of the options granted is fully expensed on the date of the grant.

The fair value of each stock option is estimated on the date of grant using the Black-Scholes valuation method with the assumptions noted in the table below. The expected life is a significant assumption as it determines the period for which the risk-free interest rate, stock price volatility, and dividend yield must be applied. The expected life is the average length of time in which executive officers, other employees, and non-employee directors are expected to exercise their stock options, which is primarily based on historical exercise experience. The company groups executive officers and non-employee directors for valuation purposes based on similar historical exercise behavior. Expected stock price volatilities are based on the daily movement of the company’s common stock over the most recent historical period equivalent to the expected life of the option. The risk-free interest rate for periods within the contractual life of the option is based on the U.S. Treasury rate over the expected life at the time of grant. Dividend yield is estimated over the expected life based on the company’s historical cash dividends paid, expected future cash dividends and dividend yield, and expected changes in the company’s stock price.

The following table illustrates the weighted-average valuation assumptions for options granted in the following fiscal periods:



	Fiscal 2018	Fiscal 2017
Expected life of option in years	6.05	6.02
Expected stock price volatility	20.60%	22.15%
Risk-free interest rate	2.21%	2.03%
Expected dividend yield	0.97%	1.01%
Per share weighted-average fair value at date of grant	$14.29	$12.55

Performance Share Awards

Under the 2010 Plan, the company grants performance share awards to executive officers and other employees under which they are entitled to receive shares of the company’s common stock contingent on the achievement of performance goals of the company and businesses of the company, which are generally measured over a three-year period. The number of shares of common stock a participant receives will be increased (up to 200 percent of target levels) or reduced (down to zero) based on the level of achievement of performance goals and vest at the end of a three-year period. Performance share awards are generally granted on an annual basis in the first quarter of the company’s fiscal year. Compensation expense is recognized for these awards on a straight-line basis over the vesting period based on the per share fair value as of the date of grant and the probability of achieving each performance goal. The per share fair value of performance share awards granted during the first quarter of fiscal 2018 and 2017 was $65.40 and $54.52, respectively.

Restricted Stock Unit Awards

Under the 2010 plan, restricted stock unit awards are generally granted to certain employees that are not executive officers. Occasionally, restricted stock unit awards may be granted, including to executive officers, in connection with hiring, mid-year promotions, leadership transition, or retention. Restricted stock unit awards generally vest one-third each year over a three-year period, or vest in full on the three-year anniversary of the date of grant. Such awards may have performance-based rather than time-based vesting requirements. Compensation expense equal to the grant date fair value, which is equal to the closing price of the company’s common stock on the date of grant multiplied by the number of shares subject to the restricted stock unit awards, is recognized for these awards over the vesting period. The per share weighted-average fair value of restricted stock unit awards granted during the first three months of fiscal 2018 and 2017 was $65.93 and $56.67, respectively.