OKLAHOMA CITY--(BUSINESS WIRE)--Sonic Corp. (NASDAQ:SONC), the nation’s largest chain of drive-in restaurants, today announced results for the third fiscal quarter ended May 31, 2015. Key highlights of the company’s third quarter of fiscal year 2015 included: Net income per diluted share was $0.38 compared with net income per diluted share of $0.30 in the prior-year period; excluding tax adjustments of $1.1 million, or $0.02 per share in the third fiscal quarter of 2015, earnings per share woul