9. Capital Structure and Per Share Data

Preferred Stock - Sonic has 3,000,000 shares of “blank check” preferred stock authorized with such designations, rights and preferences as may be determined from time to time by the Board of Directors. The Board of Directors has designated 300,000 shares of preferred stock as Class A convertible preferred stock, par value $0.10 per share (the “Preferred Stock”), which is divided into 100,000 shares of Series I Preferred Stock, 100,000 shares of Series II Preferred Stock and 100,000 shares of Series III Preferred Stock. There were no shares of Preferred Stock issued or outstanding at December 31, 2017, 2016 and 2015.

Common Stock - Sonic has two classes of common stock. Sonic has authorized 100,000,000 shares of Class A common stock at a par value of $0.01 per share. Class A common stock entitles its holder to one vote per share. Sonic has also authorized 30,000,000 shares of Class B common stock at a par value of $0.01 per share. Class B common stock entitles its holder to 10 votes per share, except in certain circumstances. Each share of Class B common stock is convertible into one share of Class A common stock either upon voluntary conversion at the option of the holder, or automatically upon the occurrence of certain events, as provided in Sonic’s charter. The two classes of common stock share equally in dividends and in the event of liquidation.

Share Repurchases - Prior to December 31, 2017, Sonic’s Board of Directors had authorized Sonic to expend up to $695.0 million to repurchase shares of its Class A common stock. As of December 31, 2017, Sonic had repurchased a total of approximately 32.3 million shares of Class A common stock at an average price per share of approximately $17.76 and had redeemed 13,801.5 shares of the Preferred Stock at an average price of $1,000 per share. As of December 31, 2017, Sonic had approximately $107.7 million remaining under the Board’s authorization.

Per Share Data - The calculation of diluted earnings per share considers the potential dilutive effect of stock options and shares under Sonic’s stock compensation plans and Class A common stock purchase warrants. Certain of Sonic’s non-vested restricted stock and restricted stock units contain rights to receive non-forfeitable dividends and, thus, are considered participating securities and are included in the two-class method of computing earnings per share. The following table illustrates the dilutive effect of such items on earnings per share for 2017, 2016 and 2015:

In addition to the stock options included in the tables above, options to purchase approximately 0.2 million and  0.4 million shares of Class A common stock were outstanding as of December 31, 2016 and 2015, respectively, but were not included in the computation of diluted net income per share because the options were not dilutive.