Which 1998 event forced Russia to default on domestic debt and devalue the ruble, triggering global market turmoil?

The 1998 event that forced Russia to default on domestic debt and devalue the ruble was the Russian financial crisis.

On August 17, 1998, the Russian government and central bank announced a restructuring of ruble-denominated domestic debt, a devaluation of the ruble, and a temporary moratorium on some foreign debt payments. The announcement followed falling oil prices, weak tax collection, political uncertainty, and the continuing effects of the Asian financial crisis.

The ruble lost much of its value, banks faced severe stress, and Russian households saw their savings damaged by inflation and financial disruption. International investors also became more risk-averse. The crisis contributed to the collapse of Long-Term Capital Management, a highly leveraged U.S. hedge fund, whose rescue was coordinated by the Federal Reserve Bank of New York.

The Russian crisis is sometimes described as a sovereign-debt crisis, but it was also a currency and banking crisis. Russia later benefited from higher oil prices and improved fiscal conditions, but those later developments do not change the identity or date of the 1998 episode.