In the regular Korean market session (09:00~15:30) on August 21, 2026, the KOSPI rose while the KOSDAQ fell. The KOSPI gained 60.37 points (0.88%) from the previous trading day to 6,912.95 points, while the KOSDAQ fell 38.95 points (4.63%) to 801.94 points. Among the tracked stocks, Samsung Electronics and SK hynix outperformed the index gain, Hyundai Motor declined, and SK Square closed unchanged.

KOSPI Holds Above 6,900 While KOSDAQ Retreats to the Low 800s

Index August 21, 2026 regular-session close Change from previous trading day on August 21, 2026
KOSPI 6,912.95 points +60.37 points (+0.88%)
KOSDAQ 801.94 points -38.95 points (-4.63%)

The KOSPI opened at 6,759.95 points on August 21, 2026, rose as high as 6,954.12 points during the session, touched a low of 6,742.44 points, and ended the regular session at 6,912.95 points. The closing level was 153.00 points above the open and 41.17 points below the intraday high. KOSPI closing data

The KOSDAQ opened at 824.05 points on the same trading day, which was also its intraday high, fell as low as 795.57 points, and closed at 801.94 points. The close was 22.11 points below the open and 6.37 points above the intraday low. KOSDAQ closing data

In the editor’s interpretation, August 21, 2026, was a trading day with a clear divergence in the closing direction of the two markets. The KOSPI’s 0.88% gain and the KOSDAQ’s 4.63% decline make it difficult to view the broader market as having moved in one direction. However, the simultaneous occurrence of the open, high, low, close, and index changes alone is not enough to conclude that a particular industry, news event, or investor group created this difference.

Samsung Electronics Rises 3.87% and SK hynix 2.31%, Both Outperforming the KOSPI

Samsung Electronics ended the regular session on August 21, 2026, at 281,500 won, up 10,500 won (3.87%) from the previous trading day. It recorded an open of 273,000 won, a high of 285,000 won, a low of 266,000 won, and regular-session volume of 49,889,173 shares. Its 3.87% gain exceeded the KOSPI’s 0.88% rise that day by 2.99 percentage points. Price records and past analysis are available at Samsung Electronics closing data and the Samsung Electronics stock hub.

SK hynix closed at 1,730,000 won on August 21, 2026, up 39,000 won (2.31%). Its open was 1,714,000 won, high was 1,773,000 won, low was 1,669,000 won, and regular-session volume was 6,955,923 shares. The close was 16,000 won above the open, and its 2.31% gain exceeded the KOSPI’s gain but fell short of Samsung Electronics’ 3.87%. SK hynix closing data and the SK hynix stock hub can be viewed together.

Based on closing data, the two tracked semiconductor stocks outperformed the KOSPI’s gain and closed in the opposite direction of the KOSDAQ’s decline. This represents relative performance within the tracked group only and does not provide grounds to conclude that gains in the two stocks directly caused the KOSPI’s rise or that semiconductor-related factors explain the entire market.

Differences Within the Tracked Group Shown by Hyundai Motor’s Decline and SK Square’s Flat Close

Hyundai Motor ended the regular session on August 21, 2026, at 415,000 won, down 2,500 won (0.60%) from the previous trading day. Its open of 412,000 won, high of 420,500 won, low of 405,000 won, and regular-session volume of 682,191 shares were recorded on the same trading day. The close was 3,000 won above the open but down from the previous trading day. Past analysis is available through Hyundai Motor closing data and the Hyundai Motor stock hub.

SK Square closed unchanged from the previous trading day at 1,123,000 won on August 21, 2026. Its open was 1,122,000 won, high was 1,141,000 won, low was 1,078,000 won, and regular-session volume was 934,222 shares. Although there was an intraday price range, the closing percentage change was 0.00%. Individual stock performance can be followed through SK Square closing data and the SK Square stock hub.

On August 21, 2026, the tracked stocks were divided between gains for Samsung Electronics and SK hynix, a decline for Hyundai Motor, and a flat close for SK Square. Therefore, the KOSPI’s rise alone should not be interpreted as indicating that all four stocks moved in the same direction.

Investor-Flow Figures and Pre-Market Article Interpretations Need to Be Read Separately

The collected investor-flow figures for August 21, 2026, show retail investors at -11,651 hundred million won, foreign investors at -1,761 hundred million won, and institutions at +2,481 hundred million won. Based on the signs of these figures, retail and foreign investors were net sellers, while institutions were net buyers. Investor-flow data by investor type for August 21, 2026 The KOSPI’s rise, institutional net buying, and net selling by retail and foreign investors were observed on the same trading day, but this single aggregate does not establish which investor group drove the index movement.

A collected pre-market Yonhap News report cited rising U.S. Treasury yields and Nasdaq weakness as background for market observations, and mentioned the possibility of sector differentiation based on foreign investor flows. This was the interpretation presented by the report; the directly observable facts in the regular-session closing data are that the KOSPI rose 0.88% and the KOSDAQ fell 4.63%. Original pre-market article

Another collected article also cited U.S. stock-market weakness as background and reported morning KOSPI and KOSDAQ moves, along with foreign and institutional selling. However, because this content was reported during the session, it should not be combined with the August 21, 2026, regular-session closing figures. Original intraday market article

Three Items to Check in the Next Regular Session

  • For the next regular-session close, it is necessary to monitor the KOSPI against its August 21, 2026, close of 6,912.95 points and intraday high of 6,954.12 points, and the KOSDAQ against its close of 801.94 points and intraday low of 795.57 points.

  • It is necessary to observe how the closing-based relative changes of Samsung Electronics at 3.87%, SK hynix at 2.31%, Hyundai Motor at -0.60%, and SK Square at 0.00% on August 21, 2026, change in the next regular session. These are observation benchmarks only and do not establish the direction of the next trading day.

  • It is necessary to check whether the investor-flow direction of retail investors at -11,651 hundred million won, foreign investors at -1,761 hundred million won, and institutions at +2,481 hundred million won on August 21, 2026, continues in the next regular-session aggregate. Investor-flow figures and prices should be observed together, but simultaneous movement on a single trading day alone cannot establish causality.