Large-cap stocks lead the rally, South Korea's Composite Stock Price Index hits a new all-time high

South Korea’s composite stock index hit a record high for three consecutive trading days on April 23, 2026, but the Kosdaq Index has not yet fully recovered to the level before the outbreak of the U.S.-Iran war, and the domestic stock market’s upward momentum is clearly concentrated in certain large-cap stocks.

According to data from the Korea Exchange, the South Korea composite stock index rose 57.88 points (0.90%) from the previous trading day to close at 6,475.81 points. During the session, it climbed as high as 6,557.76 points and, for the first time, broke through the 6,500-point mark. By contrast, after opening higher, the Kosdaq Index moved around a flat range and ultimately fell 6.81 points (0.58%) to close at 1,174.31 points. The Kosdaq Index had risen to 1,192.78 points on February 27 before the war broke out, but it fell to 978.44 points on the 4th of last month; after breaking below 1,000 points, it gradually rebounded. Although it has risen for 9 consecutive trading days recently, it has not shown the same rapid recovery trend as the composite stock index.

This difference is interpreted as the core driving force behind the recent rally being concentrated in large-cap export-oriented stocks led by semiconductors. Judging by the Korea Exchange (KRX) index, which reflects both the listed securities market and the Kosdaq market, the industry with the highest gain from April 1 to 23 was the KRX Information Technology sector, which includes Samsung Electronics and SK Hynix, up 43.18%. The construction industry, benefiting from expectations related to nuclear power, followed with a gain of 38.78%, and the semiconductor sector rose 35.81%. This ultimately means the market is not rising uniformly across the board; rather, representative industries and individual stocks with clear earnings expectations are pulling the index.

Even within the South Korea composite stock index itself, this tilt phenomenon has been confirmed. This month, the large-cap stock index within the composite index rose 29.73%, exceeding the overall composite index’s gain of 28.17%. Meanwhile, mid-cap stocks rose only 17.68%, and small-cap stocks rose just 10.68%. The gap in gains between large-cap and small-cap stocks reached about 2.8 times. Here, large-cap stocks are defined as those ranked 1st to 100th by market capitalization; mid-cap stocks are those ranked 101st to 300th; and small-cap stocks are the remaining stocks. The emergence of the claim that the index is strong but actual returns are relatively low is precisely because some mega-cap stocks are dominating the rally.

In the securities industry, it is widely believed that in the short term, leading sectors such as semiconductors and defense are very likely to continue to hold the market’s central position. This is because, ahead of the release of second-quarter earnings, stocks with upward revisions to full-year profit expectations may still attract investment funds. However, there are also views that the funds that first flowed into large-cap stocks may, over time, spread to mid- and small-cap stocks or to stocks that were relatively neglected earlier. Depending on future earnings seasons and changes in supply and demand, this trend could either sustain a strong rally centered on the composite stock index, or, conversely, become an opportunity for market heat to spread to mid- and small-cap stocks.