Wall Street trading floors were abuzz this week after an anonymous letter circulated inside KCG Holdings leaked out, revealing some severe tensions inside the computer-driven trading giant formed last year by the merger of high-speed king Getco and Knight Capital.

The letter complains about poor performance by the Getco trading operation in the past few years and the leadership of KCG chief executive Daniel Coleman, the former Getco head who took the reins of the company after the merger.