Korea Exchange Halts Program Buying for 5 Minutes in Second KOSPI Curb in Six Days

Second Program-Buying Halt in Six Days

South Korea's benchmark equity index moved hard enough on Tuesday morning to trip an automatic brake. The KOSPI added 4.53% over Monday's close to print 5,717.30 in morning trade, and at 10:13 a.m. the Korea Exchange imposed its buy-side sidecar, a five-minute pause on program buying meant to cool mechanical order flow. It was the second halt the exchange has ordered in six days. The first, triggered on October 21, did not hold: the index handed back that whole advance within two sessions, which is why Tuesday's print draws more scrutiny than its size alone would suggest.

The immediate driver sat offshore. Artificial intelligence stocks in the United States rebounded overnight, with chip names at the front of the Monday session: the Philadelphia Semiconductor Index gained 2.82%, the Nasdaq Composite advanced 0.82% to 26,169.38, and the S&P 500 finished 0.70% higher at 7,676.77. Brent crude slipped 1.01% to $114.64 a barrel in early Tuesday trade as Saudi, Pakistani and Turkish officials met in Tehran, though the contract still trades 17.28% above its level a month ago.

Back in Seoul, the two memory makers did most of the lifting. By 10:35 a.m., SK Hynix was up 7.14% at 1.366 million won, while Samsung Electronics added 4.93% to reach 223,500 won. The gain outran the rest of Asia: Japan's Nikkei 225 climbed 1.96% to 63,407.69 and Taiwan's TAIEX rose 0.47% to 46,260.03. That asymmetry cuts both ways. On October 15, the KOSPI sank 7.57% after hot US inflation data, a session in which the Nikkei lost 4.90% and the TAIEX 3.41%. With roughly half the index weighted in two chipmakers, Korean equities amplify AI sentiment in either direction.

Two Earnings Calls Decide the Rebound

The rebound starts from a deep hole. The KOSPI ended Monday close to 40% beneath its June peak after weeks of chip-led selling, and foreign investors dumped a net 695.5 billion won of Korean shares that day. Sell-side positioning has turned cautious as well: Goldman Sachs lowered its KOSPI target to 9,000 from 12,000 on Sunday, arguing that chip valuations imply a 65% drop in 2027 sector earnings, a scenario the bank itself labels overly negative.

Earnings now sit between this rally and a repeat of October. SK Hynix reports third-quarter results on October 28, and Samsung Electronics follows on October 29. Together the memory chipmakers account for about half of the index, so their guidance on 2027 memory pricing will do more for the KOSPI than any overnight move in US futures. Domestic retail investors carry the largest open exposure to that outcome. Their 2026 net purchases carry an average entry estimate near 6,550, per Global Markets Investor; Tuesday morning's level sits roughly 13% below it. Firm guidance on next year's memory pricing would loosen Goldman's bearish math. Weak outlooks would keep the 65% earnings-drop assumption priced in.

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Average entry estimate.

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SK Hynix Carries the Weight

Our reading: the five-minute sidecar confirms the move was mechanical, momentum-driven buying rather than a repricing of fundamentals, and the market itself knows it. SK Hynix is the instrument that moved hardest, up 7.14% on the day to 1.366 million won, and the level that now carries the most weight is not on any chart: it is the guidance the two memory giants deliver on October 28 and October 29. Strong 2027 memory pricing keeps Tuesday's 5,717.30 level defensible and starts closing the roughly 13% gap to retail's estimated 6,550 entry. Soft guidance, and October 21 is the template, since that rally unwound completely within two sessions.