I used to work in HFT. I have seen highly variable practices in this case, including a "mini-knight" incident in the single-digit millions due to tech debt and poor test coverage. However, the most useful change that has resulted from the KCG debacle was adding several layers of kill switches, a dedicated ops team to watch trading and flip the kill switches, and embracing devops automation.
There is a much more serious focus on having a defense in depth, and making sure that problems like this are noticed before they become an issue. Rollbacks are no longer the first action when something goes wrong: the kill switch comes first.
Dead code, tech debt, repurposed flags, and spotty test coverage are everywhere still.
There is a much more serious focus on having a defense in depth, and making sure that problems like this are noticed before they become an issue. Rollbacks are no longer the first action when something goes wrong: the kill switch comes first.
Dead code, tech debt, repurposed flags, and spotty test coverage are everywhere still.