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Korean investors trading outside market hours on Iran war market swings

Published: 03 Apr. 2026, 18:47 Updated: 05 Apr. 2026, 17:38

The closing values of the Kospi and Kosdaq indexes on April 3 are displayed on a screen in Hana Bank's trading room in central Seoul. [YONHAP]

Korean investors are increasingly trading outside regular market hours as overnight developments in the Iran war trigger sharp market swings.

In particular, social media posts by U.S. President Donald Trump during Korea’s nighttime hours have repeatedly moved the benchmark Kospi the following day, leading investors to turn to extended-hours trading to position themselves in advance, analysts said.

In March, average daily turnover in the premarket session, which runs from 8 a.m. to 8:50 a.m., rose to 6.28 trillion won ($4.2 billion), more than quadrupling from 1.46 trillion won last December, data from alternative trading platform Nextrade showed.

After-hours trading, from 3:40 p.m. to 8 p.m., also increased sharply, with average daily turnover rising to 4.98 trillion won from 1.08 trillion won over the same period. Compared with February, trading rose 23.19 percent in the premarket and 29.94 percent in after-hours sessions.

By contrast, activity during regular trading hours has weakened. Nextrade’s average daily turnover during the main session fell to 13.9 trillion won last month from 14.02 trillion won in February. On the Korea Exchange, the country's main bourse operator, average daily turnover declined to 43.85 trillion won from 46.09 trillion won over the same period.

The shift reflects how investors are adjusting to a market increasingly driven by overnight headlines, including statements from Trump that have at times triggered sharp moves in global markets.

“Premarket trading tends to be less volatile than the regular session, so on days when I expect further declines, I feel more comfortable selling early,” said an investor surnamed Jeon.

Stock prices are displayed at a screen in the Korea Exchange PR Hall in Yeouido, western Seoul, on Feb. 2. [YONHAP]

U.S. semiconductor stocks have also taken on a larger role as a leading indicator for Korean equities, particularly given the heavy weighting of chipmakers in the Kospi.

Last month, shares of Micron and Samsung Electronics moved in the same direction on 17 out of 24 trading days, suggesting a close alignment between U.S. and Korean tech stocks.

Analysts say the trend toward extended-hours trading is likely to continue as long as global uncertainty remains elevated.

“Leading stocks are closely tied to U.S. market conditions, so reliance on premarket and after-hours trading is likely to increase for the time being,” said Chung Yong-taek, senior research fellow at IBK Investment & Securities. “This trend is not limited to equities — offshore trading is also rising in the foreign exchange market.”

The Kospi closed at 5,377.30 on Friday, up 143.25 points, or 2.74 percent, from the previous session. Foreign investors turned net buyers for the first time in 12 trading days, purchasing a net 814.5 billion won.

The shift in sentiment came as reports that Iran is preparing a draft protocol with Oman to ensure safe passage through the Strait of Hormuz, a key shipping route for oil, boosted investor confidence.

U.S. markets were closed for Good Friday.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY JANG SEO-YUN [[email protected]]