Chipotle Mexican Grill Inc (NYSE:CMG) stock is up 0.9% to trade at $38.94 at last glance, after the fast casual food chain authorized an additional $500 million to buy back shares, bringing the total to $750 million.CMG is on track for its first gain in the last three sessions, bouncing off a Sept. 11, 52-week low of $38.30. Though the security is today looking to trim a 35.1% year-to-date deficit, it is still trading firmly below all key short- and long-term moving averages.Options bulls are chiming in tod ...