In South Korea’s regular trading session on August 12, 2026, the KOSPI surged 233.51 points, or 3.68%, from the previous session to close at 6,579.04. The KOSDAQ gained just 1.07 points, or 0.12%, to close at 858.91 in the same session, widening the difference between the two indexes’ percentage gains to 3.56 percentage points. All tracked stocks advanced, with SK Square rising 8.36%, Samsung Electronics 6.68%, and SK hynix 5.54%, each outperforming the KOSPI.

KOSPI Surges 3.68%, Showing a Clear Contrast With the KOSDAQ

Index August 12, 2026 Regular-Session Close August 12, 2026 Change
KOSPI 6,579.04 points +233.51 points (+3.68%)
KOSDAQ 858.91 points +1.07 points (+0.12%)

The KOSPI opened at 6,438.50 in the regular session on August 12, 2026, traded between 6,413.50 and 6,668.43, and closed at 6,579.04. The close was 140.54 points above the open and 89.39 points below the high. The difference between the high and low on August 12, 2026, was 254.93 points. The index gained 233.51 points, or 3.68%, from the previous session. KOSPI closing data

The KOSDAQ opened at 854.85 on August 12, 2026, fell as low as 839.86, and rose as high as 860.76 before closing the regular session at 858.91. The close was 4.06 points above the open and 1.85 points below the high. The difference between the high and low on August 12, 2026, was 20.90 points, while the index gained 1.07 points, or 0.12%, from the previous session. KOSDAQ closing data

The editorial interpretation based on closing data is that the market did not rise with equal strength across the board on August 12, 2026; instead, the KOSPI’s relative strength stood out. The difference between the KOSPI’s and KOSDAQ’s gains was 3.56 percentage points, but the simultaneous movements of the two indexes alone cannot establish that a particular sector or investor group caused the gap.

SK Square Rises 8.36% and Samsung Electronics 6.68%, Outpacing the Index

SK Square closed at KRW 1,024,000 on August 12, 2026, up KRW 79,000, or 8.36%, from the previous session, marking the largest percentage gain among the tracked stocks. It outperformed the KOSPI’s 3.68% gain in the same session by 4.68 percentage points. The stock opened at KRW 980,000, reached a high of KRW 1,053,000 and a low of KRW 956,000, and recorded regular-session volume of 1,050,235 shares. The close was KRW 44,000 above the open and KRW 29,000 below the high. SK Square closing data Previous coverage is available at the SK Square stock hub.

Samsung Electronics ended the regular session at KRW 255,500 on August 12, 2026, up KRW 16,000, or 6.68%, from the previous session. The stock opened at KRW 242,000, reached a high of KRW 260,500 and a low of KRW 241,000, and recorded volume of 43,618,416 shares. The close was KRW 13,500 above the open and KRW 5,000 below the high, retaining a substantial portion of the day’s advance through the close. Samsung Electronics’ gain on August 12, 2026, exceeded the KOSPI’s gain by 3.00 percentage points. Samsung Electronics closing data Previous stock-specific coverage is available at the Samsung Electronics stock hub.

An intraday Yonhap News Agency report dated August 12, 2026, cited strength in semiconductor stocks as a factor behind the KOSPI’s widening advance. A separate market-opening review published on August 12, 2026, attributed improved investor sentiment to news of strong semiconductor exports and a partial easing of concerns that the memory market had peaked. These were the respective market interpretations presented in the reports; closing data alone does not establish the reasons for the gains in Samsung Electronics or SK Square. Original Yonhap News Agency report Original market-opening review

SK hynix Also Gains 5.54%, While Hyundai Motor’s Advance Is Relatively Limited

SK hynix closed at KRW 1,504,000 on August 12, 2026, up KRW 79,000, or 5.54%, from the previous session. The stock opened at KRW 1,452,000, reached a high of KRW 1,549,000 and a low of KRW 1,440,000, and recorded regular-session volume of 6,818,967 shares. The close was KRW 52,000 above the open but KRW 45,000 below the high. The difference between the high and low on August 12, 2026, was KRW 109,000, while the stock’s gain exceeded the KOSPI’s by 1.86 percentage points. SK hynix closing data Previous coverage is available at the SK hynix stock hub.

Hyundai Motor ended the regular session at KRW 409,500 on August 12, 2026, up KRW 6,500, or 1.61%, from the previous session. The stock opened at KRW 403,500, reached a high of KRW 413,000 and a low of KRW 399,000, and recorded volume of 701,193 shares. The close was KRW 6,000 above the open and KRW 3,500 below the high. Hyundai Motor also advanced, but its gain on August 12, 2026, was 2.07 percentage points below the KOSPI’s, making it relatively limited among the tracked stocks. Hyundai Motor closing data Related coverage is available at the Hyundai Motor stock hub.

Based on closing prices, all tracked stocks advanced on August 12, 2026, but their gains ranged from Hyundai Motor’s 1.61% to SK Square’s 8.36%. The editorial interpretation is that the index’s advance was not reflected with equal strength across all tracked stocks. However, the differences in percentage gains alone cannot be used to infer capital flows between stocks or stock-specific catalysts.

Foreign and Institutional Investors Net Buyers; Individuals Post Net Sales Exceeding KRW 3 Trillion

In the final investor-flow tally for August 12, 2026, foreign investors recorded net purchases of KRW 2.8357 trillion, while institutional investors recorded net purchases of KRW 527.7 billion. Individual investors recorded net sales of KRW 3.1913 trillion in the same session. The foreign and institutional net buying and individual net selling were observed alongside the KOSPI’s 3.68% gain and the KOSDAQ’s 0.12% gain, but the simultaneous movements alone cannot establish that the final investor flows directly caused the indexes’ moves. August 12, 2026 investor-flow data

Yonhap News Agency’s intraday report on August 12, 2026, also noted net buying by foreign and institutional investors, but the intraday figures in the article and the final investor-flow figures compiled after the regular session reflect different measurement times. The closing trend should therefore be assessed using the final August 12, 2026, tally of KRW 2.8357 trillion in net purchases by foreign investors, KRW 527.7 billion in net purchases by institutional investors, and KRW 3.1913 trillion in net sales by individual investors. Original intraday market report

Three Items to Watch in the Next Regular Session

  • It will be important to see whether the KOSPI narrows the 89.39-point gap between its August 12, 2026, close of 6,579.04 and the session high of 6,668.43 at the next regular-session close. For the KOSDAQ, the comparison benchmark is the 1.85-point gap between its August 12, 2026, close of 858.91 and the session high of 860.76.

  • It will be worth watching whether SK Square’s 8.36% gain, Samsung Electronics’ 6.68% gain, and SK hynix’s 5.54% gain on August 12, 2026, continue to show greater relative strength at the next regular-session close than the KOSPI’s 3.68% gain on August 12, 2026. Another item to monitor is how Hyundai Motor’s 1.61% gain on August 12, 2026, changes its 2.07-percentage-point gap with the index.

  • It will be important to check whether the direction of the August 12, 2026, flows—KRW 2.8357 trillion in net purchases by foreign investors, KRW 527.7 billion in net purchases by institutional investors, and KRW 3.1913 trillion in net sales by individual investors—is maintained in the final tally for the next regular session. These figures serve only as a comparison benchmark for changes in investor flows and do not provide a basis for predicting the direction of the indexes or individual stocks in the next session.