On Monday (September 14, 2026), the Korea Composite Stock Price Index (KOSPI) tumbled 3.26% to close at 6,684.38 points, marking its third consecutive session of declines. The primary catalyst behind today's selloff was mounting skepticism over a slowdown in global artificial intelligence (AI) capital expenditure. The index opened sharply lower, shedding 3.13% to 6,692.61 points at the bell, with intraday losses deepening to 3.56% as it touched a yearly low of 6,654.82 points. A slight recovery in late trading helped the market pare some losses, but the benchmark still finished deep in the red.

Semiconductor and technology stocks led the decline, with hardware-heavy sectors bearing the brunt of the risk-off wave. Over the weekend, top executives at leading AI firms publicly urged a deceleration in frontier model development, shaking investor confidence in the massive AI capital spending that has underpinned outsized returns across Asian supply chains. Adding to the pressure, perpetual futures on SK Hynix traded on the Hyperliquid platform on Sunday plunged sharply, serving as an early warning signal for Asia's AI infrastructure complex and triggering a flood of selling when cash markets opened on Monday. A sharp rise in crude prices compounded the tech sector's woes, with Brent futures climbing more than 2% on the day. The elevated oil prices failed to lift overall sentiment, instead fueling inflation concerns and weighing on growth stock valuations.

Market analysts noted that regardless of whether the anxiety over slowing AI capital expenditure is ultimately justified, short-term investors typically prefer to trim risk exposure first. This cautious mood kept both the Korean equity market and Japan's Nikkei under pressure throughout the day. In a separate development, Yonhap News Agency cited an unnamed industry official as saying that Samsung Electronics and SK Hynix have turned down a proposal from the Korea Electric Power Corporation (KEPCO) to prepay a combined 25 trillion won in electricity bills over the next five years. Under the plan, KEPCO had requested Samsung Electronics to prepay 20 trillion won and SK Hynix to prepay 5 trillion won, with the funds earmarked primarily for investment in core grid infrastructure. The two chipmakers, however, argued that the uncertainty surrounding industry prospects makes large upfront payments a burden on their medium- to long-term operational strategies and have communicated their decision to KEPCO.

Meanwhile, the Korea Exchange (KRX) will extend trading hours for nearly all locally listed stocks to 8:00 p.m. starting September 14, with regular trading still concluding at 3:30 p.m. Under the currently announced schedule, normal trading will remain from 9:00 a.m. to 3:30 p.m., followed by a closing auction from 3:40 p.m. to 4:00 p.m., and a newly added post-market continuous trading session from 4:00 p.m. to 8:00 p.m. This new after-hours market is not a simple "extended hours" mechanism limited to closing price executions, but rather a continuous auction system where investors can buy and sell at varying prices. Price fluctuation limits remain capped at ±30% for the day, and the new session covers the majority of stocks listed on both the KOSPI and KOSDAQ.