South Korean stocks fell in the U.S. on Tuesday after President Yoon Suk Yeol invoked emergency powers and declared martial law, stoking fears of instability in the world’s 13th-largest economy.

The iShares MSCI South Korea ETF, The index, which includes more than 90 large and medium-sized companies in South Korea, fell 6% to hit a 52-week low.

Korea Electric Power’s American depositary receipts (ADRs) fell 5% and Korean e-commerce giant Coupang fell 6%. Shares of KT Corporation, formerly Korea Telecom, fell 3%. Posco, a South Korean steelmaker, fell more than 6%.

The president accused the opposition parties of sympathizing with North Korea and controlling parliament. Yoon did not provide details on how martial law – a temporary rule by military authorities in times of emergency – would affect governance and democracy in the country.

According to local media reports, the Korean stock exchange said it would hold an emergency meeting “to prepare response measures” and later decide whether to open the market on Wednesday.

The U.S. dollar rose 1.9% against the South Korean won on Tuesday.

—CNBC’s Hakyung Kim contributed reporting.