KOSPI posts record 18% gain as Samsung and SK Hynix rally

South Korea's benchmark KOSPI index staged a historic rally on Friday, July 31, 2026, surging nearly 18 percent to erase steep losses from earlier in the week. The index closed at 6,595.45, its largest single-day percentage and point gain on record, driven by a dramatic rebound in semiconductor stocks led by Samsung Electronics and SK hynix.

The rally followed three consecutive sessions of heavy losses that had pushed the KOSPI down roughly 17 percent, triggered by investor concerns over rising competition from Chinese memory chipmakers and broader profit-taking after a prolonged rally. The recovery was fueled by a strong overnight performance on Wall Street, where technology stocks soared after Microsoft and Amazon reported stronger-than-expected quarterly results, particularly in their cloud computing segments. This eased market anxieties about the returns on massive artificial intelligence infrastructure investments.

In Seoul, the positive sentiment translated into explosive gains for chipmaking giants. SK hynix surged nearly 30 percent, hitting its daily limit, while Samsung Electronics jumped over 26 percent, marking its biggest daily percentage gain. The buying was led by...