If other institutions or individuals have been using an exact copy of Goldman Sachs’ system in concert it’s got to be diluting the effectiveness of the program, depending on how much money is at play. Also there should be a pretty clear trading trail back to whoever might be using it. The Russian mafia is supposed to have a big brain trust they recruited after the Soviet collapse.
It’s also possible that, if GS withdraws the very heavy degree of machine trading they’ve been doing...the market collapses. Just thought I’d throw that cheerful thought in.