KOSPI plunges to six‑month low as SK hynix and Samsung shares tumble, trading halted

South Korea’s KOSPI slid to its lowest level in six months as heavy losses at major chipmakers pushed the index into an intraday plunge that halted trading briefly. SK hynix shares fell by more than 11% and Samsung shares dropped by over 9% during the sell-off, driving the market move and prompting the suspension of trading when the index dived beyond an 8% intraday drop.

Market accounts linked the rout to US inflation data that surprised to the upside, reviving investor expectations that the Federal Reserve will lift interest rates further; futures markets priced an increased chance of a 25-basis-point hike at the Fed’s next two-day meeting on Oct 28.

Reports noted that the faster-than-expected rise in US consumer prices shifted sentiment across Asian equity markets, with Tokyo and Taipei also hit as chip-related stocks slumped. One report said the Nikkei fell close to 5% and that other memory and semiconductor suppliers showed steep declines, underlining the regional reach of the sell-off.

In Seoul, trading-platform data cited by local coverage showed both Samsung Electronics and SK hynix were already down in premarket trade, and one account flagged that a continued decline would mark the KOSPI’s seventh straight daily loss, a run not seen since early September 2024.

Coverage differed in emphasis: regional outlets foregrounded the chip sector’s rout and the triggering role of US inflation data, while local market feeds highlighted the potential milestone of a seven-day losing streak for the KOSPI.

What is confirmed across the reporting is the magnitude of the individual chipmakers’ losses, the intraday 8% index drop that halted trading briefly, and the link market participants drew between US inflation surprises and renewed rate-hike expectations.

Unconfirmed in these accounts are more granular drivers inside each company’s trading flows, the composition of sellers (institutional versus retail), and any regulatory or policy moves by South Korean authorities in direct response to the day’s volatility.

The sell-off illustrates the sensitivity of Korea’s market-heavy chip sector to shifts in global rate expectations; investors tracked futures pricing that raised the odds of an October Fed tightening, and that shift in pricing cascaded through technology-heavy weightings on the KOSPI.

For now, market participants and coverage point to US inflation data and the resulting change in rate-hike probability as the proximate catalyst for the rout, with the steep falls at SK hynix and Samsung supplying the bulk of the downward pressure on the index.