Event-Driven AI

On Christmas Day 2021, Santander UK sent about 75,000 payments twice. The payments, worth around £130 million in total, came from roughly 2,000 corporate and business accounts, and the bank blamed "a scheduling issue". Santander funded the duplicate payments itself and then had to recover the money from recipients, many of whom held their accounts at other banks. The payment work was re-run, and every side effect happened again, because nothing at the point of effect knew it had already happened.