So what happened on Dec. 1, according to traders, is that a big hedge fund with a nice track record for 2014 wanted to sell its most successful investment (Apple at that point was up 50 percent year to date) in order to lock in that nice year-end performance. So the hedge fund sent a big sell order down to the trading desk.  The order was meant to be a limit order, one only to be executed at a certain specified price over a certain time, but instead was mistakenly entered in as a market order, causing the big slide in the stock. It was no coincidence this occurred on Dec 1, when investors start to close up their books for the year.  The list of top Apple holders are also some of the best hedge fund performers for the year.  The tech giant makes up 16 percent of Carl Icahn's portfolio, according to Symmetric.io, and his Icahn Associates is up 15 percent in 2014.  Greenlight Capital, which David Einhorn has guided to a 9 percent 2014 return, has 13 percent of its money in Apple, according to Symmetric.  Other top-performing hedge funds with more than 10 percent of their money in Apple include Valiant Capital, Andor Capital and Coatue Management, according to Symmetric.io data.  We'll find out just who exactly was anxious to pull the sell trigger on Apple when 13-F filings come out next year.  Read MoreApple products won't have a happy holiday: Survey  For more evidence of profit-taking in Apple, look at what stocks were up most of the day Tuesday as Apple was taking a hit: energy.  The Energy Select Sector SPDR, down more than 20 percent since July on oil's rout, was higher in Tuesday morning trading.  "Guys are flipping over their portfolio," said Grasso. "They're locking in profits in the momentum names like Apple and buying some value energy stocks."
Apple shares fell below the low they traded on Dec. 1, when a mistaken trade sent the shares down 6 percent in one day.