Amazon reported earnings on Thursday afternoon. Price initially popped to $420, then over the next ten minutes it fell all the way to $371 and change, but then over the next hour it went back up to $420 -- obviously brutal action. On Friday the stock opened at $439 and change and closed at $445. To the average observer, it closed at $390 and opened the next day at $439 ... they'd be oblivious to the drama.