OKLAHOMA CITY, 2016-Oct-23 — /EPR Retail News/ — Sonic Corp. (NASDAQ:SONC), the nation's largest chain of drive-in restaurants, today (Oct 20, 2016) announced that its Board of Directors has increased its authorization under the share repurchase program by $40 million. The additional authorization allows for up to $195 million of common stock to be repurchased through August 31, 2017. In…