Iceland’s OMX Iceland 15 index lost 76% when trading resumed on October 14, 2008.
The extraordinary decline followed the near-collapse of Iceland’s banking system during the global financial crisis. Trading in Icelandic shares had been suspended for several days as authorities dealt with the failure and restructuring of the country’s major banks.
When the exchange reopened, the index was reset to reflect the dramatically changed market. The three largest banks—Glitnir, Landsbanki, and Kaupthing—had been taken over or placed into receivership, and financial companies had dominated the Icelandic market. Their removal and repricing caused the exceptionally large recorded fall.
The result is often described as one of the steepest single-day stock-market collapses ever recorded. It was not simply an ordinary session of panic selling: the suspension, banking failures, index composition, and emergency measures all shaped the percentage shown.