South Korea's benchmark KOSPI index extended its losing streak to a fourth consecutive trading day, closing 0.9% lower at 6,627.26 points on September 15, 2026.

Global macroeconomic turbulence, a reassessment of artificial intelligence (AI) capital expenditure by major tech players, and profit-taking in previously high-flying sectors together shaped the market's direction on the day.

The primary driver behind today's weakness remained the sluggish performance of heavyweight technology stocks. Following recent global calls within the tech industry to slow the pace of AI development and re-evaluate investment returns, South Korea's semiconductor duo — Samsung Electronics and SK Hynix — both faced notable selling pressure. Foreign investors have now been net sellers for four consecutive sessions, serving as a major headwind to any market rebound momentum.

Meanwhile, the shipbuilding sector, a standout performer in previous months, witnessed a coordinated pullback. Over the past several months, a surge in international orders and rising shipping demand driven by geopolitical factors had lifted the shares of South Korea's major shipbuilders considerably. However, with a recent rebound in global oil prices and mounting uncertainty over the world trade outlook, short-term traders opted to lock in gains, pushing shipbuilding stocks broadly lower during the session and stripping the market of a defensive support pillar.