In the case of NTAP, Bloomberg retrieved unpublished financial data from the company's website and released the information shortly after 3pm ET on Nov. 18, 2010, while the market was still open.
The stock was halted, but not before dropping from roughly $54 to $49. The company released its "official" earnings release shortly after, about 3:30pm.
(Read more: Google's Miss Highlights Big Worry on Wall Street )
Disney also inadvertently posted its earnings on its website early, where it was picked up by Bloomberg.
Bottom line: a combination of carelessness and poor security measures causes these problems. (Read more: Should This Be Today's Google Doodle? )
—By CNBC's Bob Pisani
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