Key TakeawaysStarbucks and Chipotle each saw big moves in their stock prices Tuesday after the announcement that Chipotle CEO Brian Niccol is taking the top job at Starbucks.Baird analyst David Tarantino upgraded Starbucks stock after the news, while lowering his price target for Chipotle shares.Niccol will become CEO of Starbucks in September, with current CEO Laxman Narasimhan stepping down immediately. Tuesday's news that Chipotle (CMG) CEO Brian Niccol is leaving to take the same role at Starbucks (SBUX ...