KOSPI Spikes 5% on Opening, Riding Micron’s Surprise Earnings

South Koreas KOSPI surged more than 5% at the open on June 25, pushing back above 8,900 from 8,400 the prior session. Micron Technologys fiscal Q3 2026 results, which well exceeded Wall Street expectations, drove the move. The Korea Exchange (KRX) activated a buy-side sidecar shortly after the open, suspending program trading for five minutes. The mechanism triggers when the KOSPI 200 Futures index climbs 5% or more for at least one minute. Micron Results Catalyze the Move Micron reported fiscal Q3 2026 revenue of $41.46 billion, more than four times the $9.30 billion it posted in the same quarter a year earlier. Adjusted earnings per share came in at $25.11, well above the analyst consensus of around $20.78. The stock gained roughly 15% in after-hours trading following the announcement. In the early morning trading, the KOSPI traded over 8,900. SK Hynix jumped more than 10% in early morning trading and triggered a static volatility interruption (VI) at the open, briefly switching to single-price trading for two minutes. After the VI lifted, the stock moved quickly back toward its prior level. Samsung Electronics and SK Hynix reclaimed the 360,000 won and 2.8 million won levels, respectively. As BeInCrypto reported, SK Hynix recently surpassed Samsung in market cap for the first time since 2000. SK Hynix tipped 2,800,500 in early morning trading. K Hynix and Samsung Lead the Charge By investor type, individuals net bought roughly 490 billion won and institutions added around 100 billion won. Foreign investors net sold approximately 600 billion won, extending a streak of net selling that has now totaled around 12.2 trillion won over the past five trading days. The divergence mirrors the pattern seen after South Koreas previous market rebound, when retail buyers absorbed foreign selling in the early session. Han Ji-young, a researcher at Kiwoom Securities, pointed to a combination of macro tailwinds and Microns outperformance. In a favorable macro environment, including falling oil prices and the U.S. 10-year Government Bonds yield falling below 4.4%, Microns 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, Kiwoom Securities