I was developing trading systems at Goldman then. I remember that day. I got a call that evening to come in early the next day to discuss additional preventions and mitigations to implement.
Scarier was the day I put out a change request shortly before the end of the day in Asia, went out to dinner and drinks with some colleagues, stopped by my office on the way home, and merged the approved change request, during early morning trading in the US. The next day (in Asia) I woke up to discover Goldman had a roughly 28 million dollar trading loss. I spent a couple of minutes proving to myself that my change couldn't possibly have been the cause, and then realized I would have been woken in the middle of the night by a phone call if there was any possibility that my change had caused the trading loss. Since then, I don't merge code at the end of the day, and try to avoid Fridays. I was already in the habit of not coding if I had consumed any alcohol, but added the habit of not merging if I've consumed any alcohol. There's nothing like a 28 million dollar panic to get your practices in shape.