The KOSPI added 1,001.89 points in the July 31 regular session as its two largest chipmakers rebounded. The index still ended July down 22.19%.
South Korea's KOSPI closed the July 31, 2026 regular session at 6,595.45, up 1,001.89 points, or 17.91%, from the previous day. It was the largest one-day percentage gain in the index's history. Samsung Electronics rose 26.81%, SK hynix gained 29.95%, and the Kosdaq finished 11.63% higher at 719.76.
Samsung and SK hynix each gained more than 26%
Samsung Electronics closed at 262,500 won, up 55,500 won from the previous session. SK hynix added 396,000 won to finish at 1,718,000 won. Both stocks closed at their intraday highs.
| Stock or index | July 31 close | Regular-session move |
|---|---|---|
| KOSPI | 6,595.45 | +17.91% |
| Kosdaq | 719.76 | +11.63% |
| Samsung Electronics | 262,500 won | +26.81% |
| SK hynix | 1,718,000 won | +29.95% |
The KOSPI opened at 5,657.79, fell as low as 5,629.76 and climbed to an intraday high of 6,630.77. The close was 35.32 points below the session high.
U.S. technology shares rebounded a day earlier
In the July 30 U.S. regular session, the S&P 500 rose 1.7% and the Nasdaq Composite gained 2.8%. Microsoft jumped 15.5%, its biggest one-day gain in nearly 18 years, after reporting a stronger quarterly profit than analysts expected.
The Associated Press reported that the July 31 KOSPI rebound followed Wall Street's gains as artificial-intelligence-related stocks recovered from earlier losses. That reporting describes the sequence between the U.S. and Korean sessions without assigning the Korean move to a single cause.
One session recovered most of the three-day decline
The KOSPI fell 17.20% over three sessions, from 6,755.75 on July 27 to 5,593.56 on July 30. After the July 31 rebound, the index remained 160.30 points, or 2.37%, below its July 27 close.
For July as a whole, the index fell 22.19% from its June 30 close of 8,476.48. The July 31 close was 27.64% below the record closing high of 9,114.55 set on June 22, while remaining 56.51% above the 2025 year-end close of 4,214.17.
Tighter leveraged-product deposit rules took effect the same day
On July 31, South Korea raised the minimum deposit for domestic and overseas single-stock leveraged ETFs and ETNs from 10 million won to 30 million won in cash. Stocks, ETFs and bonds no longer count toward the minimum, and brokerages cannot reduce the requirement based on an investor's trading experience.
The Financial Services Commission announced on July 24 that it was moving the measure forward from an earlier August timetable. The rule took effect during the same July 31 regular session in which the KOSPI recorded its largest one-day percentage gain.