On the Seoul exchange, the trading halt hit before lunch, and traders on the floor described the mood as a mix of relief and disbelief. Samsung Electronics rose 11% in a single session, and SK Hynix climbed 7.7% — two companies that together account for roughly half of the value of the entire Korean stock market.
The June 12 rally swept across Asia. TSMC rose 2% in Taipei, and Foxconn gained 2.1%. In Tokyo, Tokyo Electron jumped 10% and Kioxia added 8%. The moves came one week after the sharpest selloff in the sector in years, a whiplash that has left portfolio managers struggling to describe the tape.
The prior week’s slide began with Broadcom. The American chip company’s earnings, released June 5, disappointed investors who had pushed semiconductor stocks to record valuations, and the selloff that followed was global and violent. AMD fell 10.9%, Intel fell 11.3%, and the SOXX semiconductor ETF dropped 10% in a single day. In Seoul, the volatility was so severe that the KOSPI triggered circuit breakers multiple times within a week, halting trading to let investors catch their breath.
The rebound has been led by memory. Samsung and SK Hynix, the world’s two largest memory-chip makers, have ridden an extraordinary surge in demand for high-bandwidth memory, the specialized chips used in AI data centers. The companies are effectively sold out, analysts said, and their pricing power has returned to levels not seen in years. The June 12 gains followed news of fresh orders and continued tight supply.
Foreign investors have been less enthusiastic. International funds have net sold at least $5 billion from Taiwanese stocks in June, according to exchange data, and the pattern extends across the region. The selling reflects profit-taking after a long run, analysts said, rather than a change in the fundamental story — but it has added to the volatility.
The whiplash has a structural cause. Semiconductor stocks have become the largest positions in Asian equity portfolios, which means every piece of sector news moves entire markets. When Samsung and SK Hynix make up half of the KOSPI, a 10% swing in either company is a 5% swing in the national index, and circuit breakers become a regular occurrence.
The sector’s swings are also a function of how fast the AI trade has moved. Valuations for memory and foundry stocks were stretched even before Broadcom’s report, and the correction that followed was the market’s way of re-pricing risk. The rebound suggests investors concluded the selloff went too far — but the speed of both moves has made positioning treacherous.
The rebound also has a technical dimension. When the KOSPI circuit breakers halted trading, short sellers who had built positions during the Broadcom selloff found themselves trapped, and the covering of those positions added force to the rally, traders said. The result is a tape that overreacts in both directions: sharp down moves feed forced selling, and sharp up moves feed short covering, with little in between. Seoul market officials have discussed whether the volatility warrants new measures, people familiar with the matter said, though nothing has been announced. For investors, the practical lesson is that position sizing matters more than usual in Asian chip markets, where a single company can swing the national index.
Analysts said the memory cycle is the key variable. Demand for AI accelerators has driven memory suppliers to allocate capacity to high-bandwidth chips, squeezing supply of conventional DRAM and pushing up prices across the board. That dynamic benefits Samsung, SK Hynix and Micron, and it has made memory the strongest corner of the chip market.
The question now is durability. Some fund managers argue the AI buildout is still early and that memory demand will keep rising for years; others point to the speed of the rebound as evidence that the market remains too hot. The circuit breakers in Seoul show that when the sector moves, it moves in both directions with equal force.
For the region’s exchanges, the concentration is both a blessing and a risk. Chip stocks have made Korea and Taiwan two of the world’s best-performing markets this year, drawing record inflows before the June pullback. They also concentrate the fate of entire national markets in the hands of a few companies and a single global cycle.
South Korea’s government has watched the volatility with attention, since the memory industry is the economy’s largest single export earner and the index’s swings move domestic sentiment. Officials have spoken publicly about supporting the semiconductor sector, and a government’s willingness to respond when a national champion wobbles is one more reason the memory trade carries a political dimension that other chip investments lack.
The coming weeks will test which story wins. Micron reports earnings on June 24, and its numbers will be read as a verdict on memory demand. Samsung and SK Hynix follow in July. Until then, traders expect more of the same: sharp moves, halted trading, and a market that swings on every headline about AI chips — the largest single bet in Asian finance.
