On what date did the United Kingdom leave the European Exchange Rate Mechanism during Black Wednesday?

The United Kingdom left the European Exchange Rate Mechanism on September 16, 1992, known as Black Wednesday.

The ERM required participating currencies to remain within agreed bands against one another. Pressure on the pound sterling intensified as markets doubted that the British government could maintain its exchange-rate commitment while also managing domestic economic conditions.

The government raised interest rates and announced other emergency measures, but the pressure continued. It suspended the pound’s ERM membership later that day. The episode caused major political damage to the Conservative government and reshaped the debate over European monetary integration.

Black Wednesday is a currency crisis rather than a conventional stock-market crash, although it caused broad market disruption. It is also sometimes confused with Britain’s later decision not to adopt the euro; the ERM withdrawal happened in 1992.