South Korea's stock market experienced a dramatic plunge of almost 10% on Tuesday. The sell-off was driven by foreign investors taking profits, influenced by overnight declines in U.S. tech stocks, with major semiconductor shares and other heavyweight stocks being heavily sold. The South Korean won also weakened against the U.S. dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) tumbled by 910.71 points, a drop of 9.99%, to close at 8,203.84. During the session, the index had reached a high of 9,175.45 points.

The Korea Exchange (KRX) triggered a market-wide circuit breaker around 2:33 PM local time. This action was taken after the KOSPI index had fallen more than 8% from the previous day's closing price.

This marks the fourth instance this year, and the tenth time on record, that the exchange has halted all stock trading for a 20-minute period.

In related news, U.S. Vice President Vance stated overnight that negotiations for a final agreement with Iran had laid a "very good foundation," with mediators also reporting progress in the talks.

Despite these diplomatic developments, U.S. stock markets closed with mixed results. The tech-heavy Nasdaq Composite Index fell 1.3% as renewed concerns about major technology companies resurfaced, highlighted by a more than 16% plunge in SpaceX's share price.

By the close on Tuesday, the South Korean won was trading at 1,539.1 won against the U.S. dollar, representing a decline of 2.1 won from the prior trading session.