The South Korea's main stock index, the KOSPI, declined on Tuesday by 2.5-6 percent to close at 2,720 points.
The tech-heavy KOSDAQ was down even more at 2.84 percent.
The KOSPI is at its lowest point since December 2020 and the KOSDAQ at its lowest since last March.
Tuesday's decline was partly because Korea saw its highest-yet number of new COVID-19 infections.
But investors are also watching factors such as the tensions in Ukraine and the meeting at the Federal Reserve this week and what the Fed decides to do with interest rates as inflation soars.
Another factor is volatility in the global markets.
U.S. stocks on Monday were on track for their worst day in almost a year and a half as the Dow plunged a thousand points but then rebounded later in the day.
The Dow finished with a gain of 0.3 percent, as did the S&P 500, and the Nasdaq was up zero.six percent.
European markets, though, did not recover and closed deep in the red.
The DAX in Frankfurt plunged 3.8 percent to hit a new 3-month low, while the CAC 40 in France fell by even more at 3.9-7 percent.
In London, the FTSE 100 was off more than 2.6 percent.
Some analyst say that this could be a crucial week for the markets.
Geopolitical risks are increasing on the Ukraine-Russia border, the FOMC meets for the first time this year on Tuesday, U.S. eastern time.
Investors will be closely watching what the Fed says in terms of tapering its asset purchases or raising rates, with any sign of a more aggressive policy likely to lead the markets lower.
Kim Yeon-seung, Arirang News.