South Korea's KOSPI raced past the 7,800 mark for the first time on Monday, closing 4.32 per cent higher at 7,822.24 in a fifth straight record-setting session and a session high of 7,899. SK Hynix and Samsung Electronics, the two giants of the country's memory-chip industry, drove the bulk of the gain — Hynix shares jumped 11 per cent to 1.88 million won, briefly carrying its market value above that of Eli Lilly.
The combined market capitalisation of the KOSPI and the KOSDAQ topped 7,000 trillion won (about $5.05 trillion) for the first time as of Tuesday morning Seoul time, a milestone the Korea Exchange said reflected the breadth of the chip-led rally rather than a handful of names. Programme trading was briefly suspended in the morning session when the gain crossed 4 per cent.
The rally has tightened against an unusually noisy macro backdrop. Brent crude rose above $104 a barrel in Asian trade after Donald Trump rejected Iran's ceasefire counter-proposal, the won weakened a quarter of a per cent against the dollar, and Korean economists at Daishin Securities revised up their 2026 GDP forecast for the second time in a month.
"The strength of the semiconductor sector stands out," Daishin's Lee Kyung-min wrote in a Monday note seen by the Korea Times. "Upward earnings momentum from the AI infrastructure investment cycle is exerting upward pressure on the broader index." Three brokerages tripled the number of target-price upgrade reports they published over the past fortnight, according to Seoul Economic Daily.
Hynix's rise reflects an underlying shift in pricing of high-bandwidth memory used in AI accelerators. Chip exports from South Korea in the first ten days of May reached $8.54 billion, up nearly 150 per cent year-on-year and the highest on record for any ten-day window. Samsung confirmed in late April that it had begun mass-shipping HBM4 modules to Nvidia for its next-generation Blackwell-class accelerators.
The rally has also been pulled higher by retail flow. Domestic individual investors, the so-called "ants", bought a net 2.7 trillion won of KOSPI shares in the first six trading days of May, according to KRX flow data — a pace that would, if sustained, mark the heaviest retail buying month since the post-COVID surge of 2020.
Not everyone is comfortable. The Bank of Korea's financial stability report, released on Friday, warned about the concentration of valuation gains in a small number of chip names and noted that household leverage to equities had returned to 2020-era highs. The central bank kept its policy rate at 2.5 per cent on April 24.
Foreign attention has been pulled by the Trump-Xi summit later in the week. Treasury Secretary Scott Bessent is scheduled to meet Chinese Vice Premier He Lifeng in Seoul on Wednesday — the city's second consecutive turn as host of US-China economic talks — adding a political backdrop to a market already trading on its own momentum.