Out of interest, what would have been the outcome for Knight if their positions had caused them to be winners? $12m fine, keep the spoils and "carry on" ?
It's not really possible to fail upwards this way. It would be like forgetting how to play chess in the middle of a game and then winning. Anomalies are universally negative in high-stakes environments, or if they're positive, only engender modest improvements.
As others have noted, not really possible. You can lose a lot of money very fast by repeatedly buying high and selling low. Everybody will trade with you, happily. The opposite, placing low buy orders and high sell orders, will simply result in nothing happening.
Knight's systems were sending small, aggressive orders on both sides of the market, so their net positions were relatively small compared to the total volume traded. They were hemmhoraging money very quickly because they were crossing the spread repeatedly.
In a big long-running error like this it is extremely unlikely that a company would have come out on top.
However, it happened fairly regularly that smaller trading errors would cause a couple (or tens of) thousand dollar win or loss for the client. If it was a loss, the client universally complains and gets comped by the company. If it was a win and it is found, the client keeps mum and the company does not raise the issue.
