South Korea's benchmark KOSPI stock index hit an all-time high on Wednesday as SK Hynix joined its memory chip rivals Samsung Electronics and Micron Technology in the $1 trillion market capitalisation club on an AI-driven rally.
The KOSPI rose as much as 5% to 8,450.26, its highest on record, with the sharp gains triggering a "sidecar" curb that temporarily halted algorithmic trading.
Shares of SK Hynix jumped as much as 11.1%, taking the chipmaker's market value to a record 1,624 trillion won ($1.08 trillion).
Strong demand for high-end memory chips used in AI chipsets like those designed by Nvidia has tightened supply and driven up prices, benefiting the world's biggest makers of the semiconductors.
South Korea's Samsung Electronics surpassed $1 trillion in market value for the first time on May 6, while U.S.-listed Micron Technology did so on Tuesday.
With Wednesday's rally, which also pushed Samsung Electronics shares up as much as 8% to a fresh record high, the electronics giant and SK Hynix accounted for 50% of South Korea's benchmark index by market capitalisation.
The KOSPI, which has emerged as the world's best performer in a global AI boom, has risen 98% so far this year, after rising 76% last year.
Samsung Electronics shares have risen 165% so far this year, while SK Hynix shares are up 245% and Micron Technology shares are up 214%.
