Knight Capital (KCG -62.8%) -12.4% AH on bankruptcy fears, even as it's reported Goldman and Sandler O'Neill have been hired to find a buyer. Knight's books have been opened up to P-E firms and at least one rival (Virtu Financial?). Bloomberg Businessweek provides the back-story for Knight's $440M loss. Between 9:30 and 10:00 AM ET yesterday, one of Knight's algorithms went haywire, pushing through 4M extra trades (550M shares) related to nearly 150 stocks. Update: Fox Business claims Virtu Financial isn't interested.