ADTRAN 2013 Annual Report 36 ADTRAN, INC. Consolidated Statements of Income  Years ended December 31, 2013, 2012 and 2011 See notes to consolidated financial statements. (In thousands, except per share amounts) 2013 2012 2011 Sales $641,744 $620,614 $717,229 Cost of sales 332,858 303,971 302,911 Gross Profit 308,886 316,643 414,318 Selling, general and administrative expenses 129,366 134,523 124,879 Research and development expenses 131,055 125,951 100,301 Operating Income 48,465 56,169 189,138 Interest and dividend income 7,012 7,657 7,642 Interest expense (2,325) (2,347) (2,398) Net realized investment gain 8,614 9,550 12,454 Other income (expense), net (911) 183 (694) Gain on bargain purchase of a business — 1,753 — Income before provision for income taxes 60,855 72,965 206,142 Provision for income taxes (15,061) (25,702) (67,565) Net Income $45,794 $47,263 $138,577 Weighted average shares outstanding—basic 59,001 63,259 64,145 Weighted average shares outstanding—diluted 59,424 63,774 65,416 Earnings per common share—basic $0.78 $0.75 $2.16 Earnings per common share—diluted $0.77 $0.74 $2.12