How to lose $172k per second for 45 minutes (2013)

When Knight used the Power Peg code previously, as child orders were executed, a cumulative quantity function counted the number of shares of the parent order that had been executed. Knight did not have a second technician review this deployment and no one at Knight realized that the Power Peg code had not been removed from the eighth server, nor the new RLP code added. On August 1, Knight also received orders eligible for the RLP but that were designated for pre-market trading.6 SMARS processed these orders and, beginning at approximately 8:01 a.m. ET, an internal system at Knight generated automated e-mail messages (called “BNET rejects”) that referenced SMARS and identified an error described as “Power Peg disabled.”

Source: sweetness.hmmz.org