Black Wednesday was the 1992 currency-market crash that forced Britain to leave the European Exchange Rate Mechanism.
On September 16, 1992, the British government struggled to keep sterling above its ERM floor against the German mark. Despite raising interest rates and spending foreign-exchange reserves, officials could not stop intense selling pressure.
Britain suspended sterling's ERM membership that evening. The event damaged the Conservative government's reputation, although the later fall in interest rates and weaker pound helped the British economy recover.
Black Wednesday is sometimes confused with a stock-exchange crash because it caused major market turmoil. It was primarily a currency and monetary-policy crisis. George Soros became famously associated with the episode after his Quantum Fund made a large profit betting against sterling.