South Korea President Yoon Suk Yeol's decision to declare martial law Tuesday, giving the president and the military broad authority over public life, affected several South Korean companies and ETFs trading on the U.S. stock market.

"I declare martial law to protect the free Republic of Korea from the threat of North Korean communist forces, to eradicate the despicable pro-North Korean antistate forces that are plundering the freedom and happiness of our people, and to protect the free constitutional order," Yoon in a surprise television speech on Tuesday.

"The National Assembly has become a monster undermining liberal democracy, and the nation is in a precarious state, teetering on the edge of collapse," the president added Tuesday.

The National Assembly voted to end the martial law, just three hours after the president invoked the measure. Under South Korea's constitution, the president must comply.

But South Korean troops were seen trying to enter the parliament, Reuters reported.

Coupang Falls As South Korean Leader Declares Martial Law

South Korea ETFs, Stocks

Korean ETFs plunged at the open in U.S. trading, though most came off lows.

iShares MSCI South Korea (EWY) fell 2.8% intraday and Franklin FTSE South Korea (FLKR) dropped 2.4% during market action on Tuesday. Both hit two-year lows earlier.

Matthews Korea Active (MKOR) declined 2.5% and JAKOTA K-Pop and Korean Entertainment (KPOP) sank 1.7%.

POSCO Holdings (PKX), a steel products maker, fell 4.8%.

Meanwhile, banking stock KB Financial (KB) declined 2.4% and Woori Financial (WF) dropped 1.6% while Shinhan Financial (SHG) fell just a fraction.

Korea Electric Power (KEP) also declined 2.9% and SK Telecom (SKM) gave up 2.1%.

However, while South Korea stocks and ETFs traded lower, companies with significant exposure to South Korea were more mixed.

Texas Instruments (TXN) fell 1.5% while Qualcomm (QCOM) edged lower. Taiwan Semiconductor Manufacturing (TSM) edged up 0.3%. Nvidia (NVDA) was flat Tuesday.

South Korea-based SK Hynix is a major chip supplier to Nvidia and is the second largest memory-chip maker in the world.

Please follow Kit Norton on X @KitNorton for more coverage.

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