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KOSPI drops 3% as Samsung, SK Hynix slide after US tech selloff

Chipmakers led the drop minutes after the Seoul open, following an overnight US tech selloff and a rise in oil prices. It is the index's third decline in four sessions.

By Rowan Ashby Published 23.10.26 00:27 UTC 5 min read

KOSPI drops 3% as Samsung, SK Hynix slide after US tech selloff — Unknown /

Key takeaways

The KOSPI fell 3.00% to 5,367.79 at 00:05 UTC (09:05 in Seoul) on Friday, October 23, 2026, minutes after the open, according to Yahoo Finance data.
Bloomberg reported that chipmakers Samsung Electronics and SK Hynix led the drop, following an overnight selloff in US technology shares and a rise in oil prices.
On Thursday, October 22, the Nasdaq Composite fell 2.6% and Brent crude rose nearly 4% to about $113 a barrel, according to NBC News and Yahoo Finance.
This is the KOSPI's third decline in four sessions since Tuesday, October 20. The cause of Friday's move has not been confirmed beyond these early reports.

Why is the KOSPI falling today?

South Korea's KOSPI drops 3% in early Friday trade: the index stood at 5,367.79 at 00:05 UTC on October 23, according to Yahoo Finance data. Bloomberg reported Samsung Electronics and SK Hynix led the slide after an overnight US tech selloff and higher oil prices.

According to Bloomberg, Korean stocks fell because heavyweight chipmakers declined. They tracked a selloff in US technology shares overnight while oil prices rose. Samsung Electronics and SK Hynix each dropped more than 2% in early trading, Bloomberg said. Together the two companies make up a large share of the index's weight, so moves in their shares strongly affect the benchmark.

What happened overnight on Wall Street

US markets on Thursday, October 22, set the tone for Asia. According to NBC News, the S&P 500 closed down 1.2% and the Nasdaq Composite lost 2.6%. Yahoo Finance's market coverage put the Nasdaq close at 26,008.86, down 694 points.

Both outlets tied the selloff to two concerns:

AI spending and funding. Meta Platforms shares fell about 7% after its quarterly results, and Tesla closed about 3% lower after saying it would rein in capital spending, according to Yahoo Finance. NBC News reported that Nvidia chief executive Jensen Huang told CNBC that capital to finance the AI investment boom was becoming "scarce". Chip-equipment makers including Lam Research, Applied Materials and KLA fell between about 6% and 9%, Yahoo Finance reported.
Oil and the Middle East. NBC News reported that Brent crude rose nearly 4% to about $113 a barrel, its highest since May, and that WTI closed above $99. The rise followed reports that the United States and Israel were preparing to resume strikes on Iran after the November 3 US midterm elections. Yahoo Finance also cited attacks on a Saudi airport and an Aramco oil field.

How the KOSPI has moved this week

Session (KST)	KOSPI level	Change	Source
Tue, Oct 20 (close)	about 5,553	-3.73%	Trading Economics
Wed, Oct 21 (close)	5,735.66	+3.29%	Seoul Economic Daily
Thu, Oct 22 (close)	5,533.77	-3.52%	Seoul Economic Daily, SBS
Fri, Oct 23 (00:05 UTC)	5,367.79	-3.00%	Yahoo Finance

Data as of 2026-10-23 00:05 UTC. Intraday levels can change quickly during the session.

What we know and what we don't know yet

What we know

The drop began at the open and was led by the two largest chipmakers, according to Bloomberg.
US technology and semiconductor stocks fell sharply on Thursday, and crude oil reached its highest level since May, according to NBC News and Yahoo Finance.
Thursday's 3.52% fall in Seoul came the same day the Bank of Korea held its base rate at 3.00%. SBS reported that Governor Shin Hyun-song signalled that further hikes were possible.

What we don't know yet

Foreign and institutional trading flows for Friday's session have not yet been published.
No Korean regulator or exchange statement on Friday's move had been reported as of 00:05 UTC.
Beyond the early reports cited here, the cause of the move has not been confirmed. Where the index closes depends on trading later in the session.

Background

The KOSPI has been volatile since early October. On October 23, Seoul Economic Daily reported that the decline began on October 7. The paper said KB Securities analyst Lee Eun-taek warned in a report that a W-shaped correction was more likely than a quick rebound, noting that "there have been cases where the second bottom was lower than the first". In the same report, KB said lower oil prices or easing memory-chip concerns could support a recovery.

SBS reported that Thursday's selling also followed the end of share buyback programmes at Samsung Electronics and SK Hynix, which had been a source of buying in the market. It also cited doubts about returns on AI investment after Meta's results. Bullquill covered Thursday's early move in KOSPI slips after rebound as the Bank of Korea holds at 3% and the US selloff in Nasdaq falls on AI spending worries.

What it means

Friday's open shows how closely Korean stocks now track US technology shares and AI spending news. When US chip stocks fall, Samsung Electronics and SK Hynix tend to follow, and the KOSPI moves with them. Higher oil prices add pressure: KB Securities, as reported by Seoul Economic Daily, linked the market's recovery to easing inflation pressure, such as lower oil prices. Over the coming week, market reports point to earnings from Microsoft and Amazon, shareholder return plans from Samsung and SK Hynix, and developments involving Iran. For more context, see our chip stock slump explainer, our coverage of Meta's AI debt costs, and the latest South Korea stocks daily brief. For how the week ended, see our KOSPI weekly brief.

Frequently asked questions

Why is the KOSPI down today?

On October 23, 2026, Bloomberg reported that Korean stocks fell as Samsung Electronics and SK Hynix declined, tracking an overnight selloff in US technology shares while oil prices rose. No other cause had been confirmed as of 00:05 UTC.

What happened on Wall Street on October 22, 2026?

According to NBC News, the S&P 500 fell 1.2% and the Nasdaq Composite fell 2.6%. Investors reacted to concerns about AI spending and to Brent crude rising to about $113 a barrel on reports of possible renewed strikes on Iran.