South Korea’s KOSPI surged about 3% on Monday, September 7, as investors returned to semiconductor stocks on renewed optimism over artificial intelligence demand. The benchmark opened 3.34% higher at 6,910.78 and was up 2.97% at 6,886.09 by late morning in Seoul. Samsung Electronics gained 4.91%, while SK Hynix jumped 8.4% after OpenAI unveiled its GPT-6 Astra model, which revived expectations for another leg of AI-related memory demand.
The rally was broad but technology-led. The PHLX Semiconductor Index rose 3.38% on Friday after the OpenAI launch. In Seoul, SK Square gained 5.67% and Hanmi Semiconductor added 5.43%. Foreign and institutional investors were net buyers of roughly 768.4 billion won early in the session, while retail investors sold about 812.2 billion won, according to Seoul Economic Daily.
Analysts reinforced the bullish case. KB Securities reported memory inventories at Samsung and SK Hynix had fallen below 10 days of supply, and projected next year’s DRAM and NAND demand would exceed supply by more than 10 percentage points. Mirae Asset raised its Samsung target to 400,000 won and SK Hynix target to 3.1 million won. DB Securities lifted its SK Hynix price target to 2.3 million won from 2 million won, citing HBM4 shipment growth. Goldman Sachs Asia-Pacific equity strategist Timothy Moe stood by a 12-month KOSPI target of 12,000, implying close to 80% upside, arguing investors underestimate how long the AI-driven memory cycle can last.
OpenAI President Greg Brockman described GPT-6 Astra as a potential early form of artificial general intelligence. Meritz Securities analyst Hwang Soo-wook argued that cheaper AI could encourage users to assign longer and more complicated jobs to agents, expanding total compute workloads rather than shrinking them. Kiwoom Securities analyst Han Ji-young said Astra had brought AI demand momentum back into focus and suggested selling pressure on semiconductor stocks may be nearing exhaustion.
The macro backdrop remained less comfortable. Brent crude rose about 0.7% towards $97 a barrel and WTI gained roughly 0.8% to above $92 after U.S.-Iran attacks around the Strait of Hormuz. The 10-year Treasury yield remained near 4.78%, while markets assigned roughly a 58% probability to a September Federal Reserve rate increase.
