The Korea Composite Stock Price Index (KOSPI) surged 459.28 points, or 5.42%, to close at 8,930.30 on June 25, extending a 3.26% gain from the previous session. The index briefly recaptured the 9,000-point threshold, climbing as high as 9,044.04, before paring some of those gains by the close.

The move followed a 9.99% crash on Tuesday that wiped out nearly all of the prior week’s record-setting advance, which had pushed the KOSPI to an all-time closing high of 9,114.55 on Monday. The market has seesawed through June as investors vacillate between confidence in AI-driven semiconductor demand and fears that the rally has outpaced fundamentals.

Trade volume reached 449.3 million shares worth 50.4 trillion won (US$32.7 billion), with losers still outnumbering winners 588 to 289. Institutional investors were net buyers, purchasing 3.3 trillion won worth of stocks, while foreigners and individuals sold a net 819.7 billion won and 2.5 trillion won, respectively.

Micron Technology, the world’s No. 3 memory-chip maker, released quarterly results on Wednesday that sent its shares up 14% in after-hours U.S. trading. The company, a major beneficiary of rising demand for high-bandwidth memory used in AI data centers, reported revenue and profit above analyst forecasts. Alongside Samsung Electronics and SK hynix, Micron forms the core of a global memory-chip trio whose fortunes have been tied to the AI infrastructure spending boom.

“Micron’s strong financial report pushed up semiconductor shares here,” said Kim Seok-hwan, an analyst at Mirae Asset Securities. “Airline shares also rose as the Strait of Hormuz seemed to reopen and global oil prices dropped.”

Samsung Electronics, the world’s largest memory-chip maker, jumped 5.29% to 358,500 won. SK hynix, the No. 2 player, surged 13.06% to 2.9 million won. SK Square, the parent company of SK hynix, advanced 5.56% to 1.9 million won, and Samsung C&T, which holds a stake in Samsung Electronics, soared 7.79% to 519,000 won.

Flag carrier Korean Air vaulted 6.4% to 29,100 won, and Asiana Airlines rose 6.2% to 7,710 won. Brokerages also saw gains: Samsung Securities rose 3.07% to 110,800 won, and Kiwoom Securities gained 7.48% to 337,500 won.

The Korean won edged lower, quoted at 1,542.7 per U.S. dollar as of 3:30 p.m., down 0.9 won from the previous session. Bond prices closed higher, with the yield on three-year Treasury bonds falling 1.5 basis points to 3.757% and the return on benchmark five-year government bonds declining 2.2 basis points to 3.992%.