The 1992 stock-market and currency-market crash following the United Kingdom's exit from the European Exchange Rate Mechanism was called Black Wednesday.
On September 16, 1992, the British government withdrew sterling from the ERM after failing to keep the currency above its required lower limit. The government had raised interest rates and spent billions supporting the pound, but speculative pressure continued.
The episode caused a major political setback for Prime Minister John Major's Conservative government. It also produced large losses for the British Treasury and damaged confidence in the government's economic management. George Soros became especially famous for profiting from a large short position against sterling.
Black Wednesday was principally a currency crisis rather than a single-day share-market collapse. It is included in stock-market-crash histories because the exchange-rate shock affected investor confidence, interest rates, and financial markets across Britain and Europe.