Knight Capital lost $460 million in 45 minutes on August 1, 2012 due to a software deployment issue. A new version of code was deployed to only 7 of 8 servers, activating old obsolete "power-peg" functionality that moved stock prices unexpectedly. This caused major disruptions and Knight's stock fell 70%. The incident highlights the importance of proper code deployment practices like reviewing all deployments, addressing errors, and testing impact before manual undeployment. Adopting DevOps practices around configuration, deployments, testing, and monitoring could help prevent such issues.