In Korea’s regular session (09:00–15:30) on September 21, 2026, the KOSPI rose 113.49 points (1.65%) from the previous trading day to close at 7,007.72 points, while the KOSDAQ gained 9.15 points (1.11%) to finish at 836.27 points. Among the tracked stocks, Samsung Electronics and SK Square rose more sharply than the KOSPI, while Hyundai Motor declined against the index’s direction.

Index September 21, 2026 regular-session close Change from previous trading day September 21, 2026 regular-session high·low
KOSPI 7,007.72 points +113.49 points (+1.65%) 7,027.58 points·6,938.34 points
KOSDAQ 836.27 points +9.15 points (+1.11%) 838.32 points·822.41 points

KOSPI Finishes Above 7,000 as KOSDAQ Also Rises

The KOSPI opened at 6,938.34 points in the regular session on September 21, 2026, climbed as high as 7,027.58 points intraday, and closed at 7,007.72 points. It gained 1.65% from the previous trading day, with the close 19.86 points below the intraday high. KOSPI regular-session closing data

The KOSDAQ opened at 830.71 points on the same trading day, moved through an intraday low of 822.41 points and a high of 838.32 points, and ended the regular session at 836.27 points. Its 1.11% gain from the previous trading day was 0.54 percentage points smaller than the KOSPI’s 1.65% increase. While both indexes closed higher, this concurrent movement alone does not establish that a particular sector or investor group directly drove the gains. KOSDAQ regular-session closing data

Intraday reports cited the KOSPI’s approach to the 7,000 level and foreign and institutional buying as factors behind the advance. However, those articles described conditions early in the session and should be read separately from the regular-session closing figures below. Original intraday market report

Samsung Electronics Gains 4.41% and SK Square 4.08%, Outpacing the Index

Samsung Electronics closed at 272,500 won on September 21, 2026, up 11,500 won (4.41%). It recorded an open of 263,500 won, an intraday high of 275,000 won, an intraday low of 259,500 won, and trading volume of 31,047,411 shares. Its closing gain was 2.76 percentage points larger than the KOSPI’s 1.65% and 3.30 percentage points larger than the KOSDAQ’s 1.11%. Price movement alone cannot determine the trend of the broader semiconductor sector or the reason for the advance, but it was the largest gain among the tracked stocks. Historical analysis is available through Samsung Electronics closing data and the Samsung Electronics stock hub.

SK Square rose 44,000 won (4.08%) to 1,123,000 won on September 21, 2026. Its open and intraday low were both 1,078,000 won, its intraday high was 1,137,000 won, and trading volume was 652,916 shares. Its closing gain was 2.43 percentage points higher than the KOSPI’s and 2.97 percentage points larger than the KOSDAQ’s. Related records are available through SK Square closing data and the SK Square stock hub.

An early-session Yonhap News report noted strength in both Samsung Electronics and SK hynix. This reflects the intraday conditions described in the original article and cannot be interpreted as definitive causality explaining the difference between Samsung Electronics’ +4.41% close and SK hynix’s +0.59% close. Original intraday semiconductor-stock report

SK hynix Posts a Limited Gain While Hyundai Motor Declines Against the Index

SK hynix closed at 1,868,000 won on September 21, 2026, up 11,000 won (0.59%). It recorded an open of 1,858,000 won, an intraday high of 1,888,000 won, an intraday low of 1,847,000 won, and trading volume of 3,867,710 shares. Although it closed higher, its gain was 1.06 percentage points smaller than the KOSPI’s and 0.52 percentage points smaller than the KOSDAQ’s. Historical analysis is available through SK hynix closing data and the SK hynix stock hub.

Hyundai Motor closed at 360,500 won on September 21, 2026, down 4,500 won (-1.23%). It recorded an open of 365,000 won, an intraday high of 369,500 won, an intraday low of 358,500 won, and trading volume of 699,915 shares. It was the only decliner among the four tracked stocks on a day when both the KOSPI and KOSDAQ rose, and the difference from the KOSPI’s closing return was 2.88 percentage points. However, a closing move in the opposite direction from the index alone cannot identify the reason for the individual decline. See Hyundai Motor closing data and the Hyundai Motor stock hub.

Separating Net-Buying Direction From Market Reports

Investor net-trading totals on September 21, 2026 were individuals -29,910 units of KRW 100 million, foreign investors -1,655 units of KRW 100 million, and institutions +14,982 units of KRW 100 million. Individuals and foreign investors were recorded as net sellers, while institutions were net buyers. These flow figures are closing data that can be reviewed alongside the same day’s KOSPI +1.65% and KOSDAQ +1.11%, but one day’s investor flows and index changes do not establish that trading by any group directly caused the index gains. September 21, 2026 investor trading data

One intraday article cited simultaneous foreign and institutional buying as a factor behind the KOSPI’s advance. By contrast, foreign investors in the collected regular-session flow totals were net sellers at -1,655 units of KRW 100 million. Therefore, the intraday interpretation in the article and the regular-session closing totals should be distinguished according to their respective reference times, and neither source alone can conclusively identify the cause of the closing gain. Original intraday article citing foreign and institutional buying

Another intraday report cited US technology-stock trends as a factor behind the KOSPI’s advance. This was the market interpretation presented in the report; the provided September 21, 2026 regular-session closing data alone cannot measure the extent to which that factor contributed to the KOSPI’s +113.49-point gain. Original intraday market report on US technology stocks

Three Items to Review in the Next Regular Session

  • The KOSPI’s September 21, 2026 close of 7,007.72 points and intraday high·low of 7,027.58 points·6,938.34 points, as well as the KOSDAQ’s close of 836.27 points and intraday high·low of 838.32 points·822.41 points, can be compared with the next regular session’s figures. KOSPI data and KOSDAQ data

  • For the tracked stocks, compare how the September 21, 2026 closing returns of Samsung Electronics +4.41%, SK Square +4.08%, SK hynix +0.59%, and Hyundai Motor -1.23% differ from the indexes in the next regular session.

  • Investor net trading for individuals -29,910 units of KRW 100 million, foreign investors -1,655 units of KRW 100 million, and institutions +14,982 units of KRW 100 million on September 21, 2026 can be compared with the next regular-session totals. Price and investor flows can be reviewed together, while avoiding conclusions of causality based solely on concurrent changes during one trading day. Investor trading data