The Thai baht was floated on July 2, 1997, helping trigger the Asian financial crisis.
Thailand had maintained the baht within a managed exchange-rate system, but heavy pressure on its foreign-exchange reserves made the arrangement difficult to defend. On July 2, the government allowed the currency to float and the baht soon depreciated sharply. Investors then reassessed other Asian economies with high foreign-currency debt, property speculation, or fragile financial systems.
The crisis spread through Thailand, Indonesia, South Korea, Malaysia, and other markets. Stock prices fell, currencies weakened, companies struggled to repay dollar-denominated loans, and several countries sought assistance from the International Monetary Fund. The consequences varied by country, but the episode showed how rapidly modern capital flows could transmit financial stress.
The rupiah, won, and ringgit were also heavily affected, which can make the question confusing. However, the baht was the currency whose forced float is conventionally used to mark the crisis’s beginning.