The 15 minutes on a Citi trading desk that sparked a flash crash

On a public holiday in the UK, when the markets were expected to be calm, a significant trading error occurred at Citigroup. A trader on the Delta One desk attempted to manually hedge the bank’s exposure to the MSCI World Index. In the process, the trader mistakenly entered a figure intended as the notional value ($58 million) into the quantity field, resulting in the creation of an erroneously large basket of equities valued at $444 billion.