mastercard incorporated notes to consolidated financial statements 2014continued in september 2010 , the company 2019s board of directors authorized a plan for the company to repurchase up to $ 1 billion of its class a common stock in open market transactions . the company did not repurchase any shares under this plan during 2010 . as of february 16 , 2011 , the company had completed the repurchase of approximately 0.3 million shares of its class a common stock at a cost of approximately $ 75 million . note 18 . share based payment and other benefits in may 2006 , the company implemented the mastercard incorporated 2006 long-term incentive plan , which was amended and restated as of october 13 , 2008 ( the 201cltip 201d ) . the ltip is a shareholder-approved omnibus plan that permits the grant of various types of equity awards to employees . the company has granted restricted stock units ( 201crsus 201d ) , non-qualified stock options ( 201coptions 201d ) and performance stock units ( 201cpsus 201d ) under the ltip . the rsus generally vest after three to four years . the options , which expire ten years from the date of grant , generally vest ratably over four years from the date of grant . the psus generally vest after three years . additionally , the company made a one-time grant to all non-executive management employees upon the ipo for a total of approximately 440 thousand rsus ( the 201cfounders 2019 grant 201d ) . the founders 2019 grant rsus vested three years from the date of grant . the company uses the straight-line method of attribution for expensing equity awards . compensation expense is recorded net of estimated forfeitures . estimates are adjusted as appropriate . upon termination of employment , excluding retirement , all of a participant 2019s unvested awards are forfeited . however , when a participant terminates employment due to retirement , the participant generally retains all of their awards without providing additional service to the company . eligible retirement is dependent upon age and years of service , as follows : age 55 with ten years of service , age 60 with five years of service and age 65 with two years of service . compensation expense is recognized over the shorter of the vesting periods stated in the ltip , or the date the individual becomes eligible to retire . there are 11550000 shares of class a common stock reserved for equity awards under the ltip . although the ltip permits the issuance of shares of class b common stock , no such shares have been reserved for issuance . shares issued as a result of option exercises and the conversions of rsus and psus are expected to be funded primarily with the issuance of new shares of class a common stock . stock options the fair value of each option is estimated on the date of grant using a black-scholes option pricing model . the following table presents the weighted-average assumptions used in the valuation and the resulting weighted- average fair value per option granted for the years ended december 31: .
what is the average expected dividend yield during 2008-2010?
the risk-free rate of return was based on the u.s . treasury yield curve in effect on the date of grant . the company utilizes the simplified method for calculating the expected term of the option based on the vesting terms and the contractual life of the option . the expected volatility for options granted during 2010 and 2009 was based on the average of the implied volatility of mastercard and a blend of the historical volatility of mastercard and the historical volatility of a group of companies that management believes is generally comparable to .