KOSPI surges 5% to 8,900 as Micron earnings ignite chip rally

South Korea's KOSPI surged 5.1% to 8,900 at the open on Thursday, pushing back toward its all-time high after Micron Technology's blockbuster quarterly results reignited demand for semiconductor stocks.

The Korea Exchange activated a buy-side sidecar shortly after the open, suspending program trading for five minutes after the KOSPI 200 Futures index climbed 5% or more for at least one minute. The index had closed at 8,400 in the prior session.

"In a favorable macro environment, including falling oil prices and the U.S. 10-year yield falling below 4.4%, Micron's earnings surprise and the more than 5% strength in the KOSPI200 night futures combined to send the index surging at the open," Han Ji-young, a researcher at Kiwoom Securities, said.

SK Hynix jumped more than 10% in early trading, triggering a static volatility interruption that briefly switched the stock to single-price auction for two minutes. Samsung Electronics reclaimed the 360,000 won level. By investor type, individuals net bought roughly 490 billion won and institutions added about 100 billion won, while foreign investors net sold approximately 600 billion won, extending a streak that has now totaled around 12.2 trillion won over the past five trading days.

Micron reported fiscal Q3 revenue of $41.46 billion, more than four times the $9.30 billion it posted a year earlier. Adjusted earnings per share came in at $25.11, well above the analyst consensus of about $20.78. The stock gained roughly 15% in after-hours trading. The chipmaker also said customers had committed $22 billion for its memory chips, signaling sustained demand for AI-related hardware.

The rally extended across Asia. Japan's Nikkei rose more than 2%, while MSCI's broadest index of Asia-Pacific shares outside Japan gained 1.3%. Futures for the S&P 500 rose 0.5% and Nasdaq futures jumped 1.8%, suggesting the tech rally could carry into the U.S. session. Brent crude futures dipped 0.5% to $73.34 a barrel, while the U.S. 10-year Treasury yield held below 4.4%.

The KOSPI has gained 184% over the past 12 months, making it the world's best-performing major index in 2026. It is now approaching its all-time high of 9,387. Whether it can break through depends on whether the Micron-driven momentum can overcome persistent foreign selling and lingering valuation concerns that have weighed on AI stocks in recent sessions. Analysts remain skeptical of a sustained rally, with some pointing to stretched valuations across the AI complex as a risk to further upside.

This article is for informational purposes only and does not constitute investment advice.