Which 1997 event caused major stock-market turmoil after Thailand devalued the baht?

The 1997 event triggered by Thailand’s baht devaluation was the Asian financial crisis.

Thailand abandoned its fixed exchange-rate defense on July 2, 1997, allowing the baht to float after intense pressure on its foreign-exchange reserves. The currency fell, and financial stress spread across several Asian economies. Stock markets in Thailand, Indonesia, South Korea, Hong Kong, and elsewhere suffered severe losses.

The crisis involved more than stock prices. Many banks and companies had borrowed heavily in foreign currencies, often with short maturities. When local currencies weakened, the domestic cost of repaying those debts rose sharply. Falling asset prices and capital flight deepened the damage.

The episode is also called the Asian financial crisis or Asian financial crisis of 1997–1998. It later affected Russia and contributed to instability in other emerging markets. The crisis was not simply a stock-market crash: exchange-rate pressure, banking weakness, property bubbles, and foreign-debt exposure all played central roles.