Comment by kevinguh

Take a look at Knight Capital for a case study -- tl;dr, they deployed an update that accidentally triggered a blind spot in their trading system which had been inactive for almost a decade. By the time their engineers were able to stop it, Knight was on the hook for several billion dollars' worth of trades and had to close their positions for a loss of almost half a billion dollars. From my understanding they ended up merging with another firm to cover their losses so while they weren't entirely "killed", they were still severely kneecapped by tech debt.