South Korea's Kospi index recorded an 18% single-day gain on 31 July 2026, its best-ever daily performance, driven by sharp rallies in major technology and semiconductor companies. The surge followed a severe sell-off earlier in the week, during which the index had dropped as much as 12.6% in a single session on 29 July after disappointing earnings from SK Hynix. Bloomberg Markets reported the July gains in the context of renewed AI sector momentum and strengthening global demand for AI infrastructure.
Samsung Electronics and SK Hynix, South Korea's two largest chipmakers and dominant constituents of the Kospi, each posted share price gains exceeding 20% on 31 July. SK Hynix trades on the Korea Stock Exchange under the ticker 000660.KS, while Samsung Electronics trades as 005930.KS; both companies are primary suppliers of high-bandwidth memory chips used in AI server hardware. The broader Kosdaq index also participated in the rebound.
The scale of the single-day move followed extreme volatility across the week. On 30 July, Bloomberg Markets reported the Kospi had declined 33% across July, reaching its cheapest recorded valuation. The reversal on 31 July coincided with a rebound in US chip stocks and strong Amazon earnings results, which lifted US equity futures simultaneously.
Sources: Bloomberg Markets, Marketwatch TOP, Guardian Business, Cnbc TOP, investinglive.com