Only 265 stocks advance in September, while 651 issues—or 69.1%—retreat
Samsung Electronics and SK hynix defend the headline index as trading turnover falls to less than half of June levels
Although the KOSPI managed to eke out a monthly gain in September, underlying market conditions revealed a stark divergence. While heavyweight semiconductor shares such as Samsung Electronics and SK hynix bolstered the headline index, roughly seven out of ten stocks listed on the KOSPI suffered price declines.
The broad-based rally seen as recently as August gave way in just one month, with the number of advancing issues plunging to about one-third of the previous level. Amid trading values dropping to yearly lows, the widening gap between the headline index and the reality felt by everyday investors has become increasingly pronounced.
Advancing Stocks Plunge from 743 to 265: A Market Reversal in Just One Month
According to the Korea Exchange on the 2nd, only 265 stocks on the KOSPI market rose during September, accounting for a meager 28.1% of the total. Conversely, declining issues reached 651, or 69.1%, while 26 stocks (2.8%) finished flat.
The shift from a month prior is striking. In August, 743 KOSPI-listed stocks (79.0%) advanced, with a mere 171 issues (18.2%) moving lower.
Over the course of a single month, advancing issues tumbled 64.3% from 743 to 265. Over the same period, declining stocks surged 280.7% from 171 to 651.
Yet, the KOSPI managed a 0.26% gain for the month—a clear misalignment between the benchmark index and individual stock performance.
The index was single-handedly propped up by large-cap semiconductor shares. Throughout September, SK hynix advanced 6.09%, while Samsung Electronics gained 3.27%. Samsung Electro-Mechanics also rose 3.77%.
Driven by the strength of chipmakers with heavy market capitalization weightings, the KOSPI maintained a positive return despite the widespread decline across the broader market.
Lee Kyung-min, an analyst at Daishin Securities, noted, "Amid an unstable macroeconomic environment accompanied by profit-taking, a distinct lack of momentum outside of AI semiconductors limited sector rotation into non-chip industries."
In fact, the only sectors that outperformed the KOSPI in September were semiconductors and energy.
Trading Turnover Shrinks from 50 Trillion Won to 21 Trillion Won as Market Vigor Fades
As warmth across individual stocks faded, trading activity also dried up. The average daily trading value on the KOSPI dropped to 21.29 trillion won in September, the lowest monthly level this year.
After peaking at 50.35 trillion won in June, average daily trading values steadily declined to 36.88 trillion won in July and 25.85 trillion won in August, before sliding to the 21 trillion won range in September—less than half of June's volume.
Market analysts attribute the sluggish trading to mounting external uncertainties—including geopolitical tensions in the Middle East, surging global oil prices, and rising U.S. long-term bond yields—alongside growing debates over the pace of AI investments and a wait-and-see stance ahead of the Chuseok holiday.
The disconnect between the index and individual stocks was also evident during trading sessions. On the 21st of last month, when the KOSPI closed at 7,007.72 to reclaim the 7,000 threshold, only 310 stocks advanced while 552 declined.
Semiconductors Pull Up the Index While Broad Gains Remain Limited
The defining characteristic of September's market was revealed not by the magnitude of the index's rise, but by the extreme concentration of its gains.
Buoyed by strong export and earnings expectations, semiconductor stocks maintained their strength, but buying pressure failed to diffuse into non-chip sectors—explaining why a significant majority of stocks lagged behind even as the index advanced.
Industry watchers are nonetheless raising the possibility of a eventual rotation into non-semiconductor sectors as chip dominance persists.
Analyst Lee Kyung-min suggested that solid export growth and visible earnings improvements in non-chip industries could spark a rotation led by undervalued, overlooked stocks.
Yang Il-woo, an analyst at Samsung Securities, also noted that the benefits of diversification could grow in October, adding that a moderation in the heavy semiconductor concentration within the KOSPI could elevate the relative returns of non-chip sectors.
While the KOSPI finished September higher, less than 30% of all stocks actually saw price gains. How broadly buying momentum expands beyond semiconductors in October will serve as a key benchmark in gauging the gap between the headline index and investors' on-the-ground experience.
