The United Kingdom's September 16, 1992 currency and market crisis was called Black Wednesday.
On that day, heavy pressure forced the British government to withdraw the pound sterling from the European Exchange Rate Mechanism, or ERM. The government had tried to keep sterling within an agreed trading band, but investors believed the pound was overvalued and that the target could not be defended.
The Bank of England raised interest rates sharply and intervened by buying pounds, but the measures failed to stop the selling. Chancellor Norman Lamont announced the suspension of the pound's ERM membership later that day.
Black Wednesday is sometimes remembered as a currency crisis rather than a conventional share-price crash. Its market turmoil nevertheless produced major losses for the government and became a defining episode in modern British financial history. The episode also strengthened the reputation of speculator George Soros, who bet against sterling.