This is a little long, but it's a must read for anyone interested in real-life consequences of computer bugs. Basically, new software was pushed to seven of ei

This is a little long, but it's a must read for anyone interested in real-life consequences of computer bugs. Basically, new software was pushed to seven of eight servers at Knight, one of the biggest players on Wall Street. A flag activating the new software was repurposed from very old inactive software that was still on the servers. The new software ran fine on seven servers, but the flag activated the old software on the eighth server, which promptly started doing something completely insane as far as financial markets are concerned. A few minutes later people removed the new software. But didn't change the flag. So then: (the old software) jumped in to fill that void and was now running on all eight servers simultaneously, buying on the offer, selling on the bid. Knight lost over $400 million in under an hour, and was forced to eventually sell out to one of their biggest competitors.