[E-Daily Reporter kyoungeun kim ] As the stock market prepares to open in September, investors’ calculations are becoming more complex. Based on past statistics, September is considered a typical “bearish month” in the KOSPI market.
According to the Korea Exchange on the 31st, based on historical average price fluctuations for the KOSPI and KOSDAQ, the average monthly change for the KOSPI in September was -0.59%. This is the second-lowest figure among the 12 months, following August (-1.43%). These figures represent the average monthly returns for the KOSPI from 1980 (when the composite index was first calculated) through 2025, and for the KOSDAQ from 1997 through 2025.
The downtrend was even more pronounced in the KOSDAQ market in September. During the same period, the KOSDAQ’s average monthly change for September was -3.21%, marking the worst performance among the 12 months.

In contrast, November was a month marked by a notable upward trend. The KOSPI rose an average of 2.48% in November, posting its highest annual gain, while the KOSDAQ also rose 2.28%, recording its second-highest gain after January (2.69%). In addition, the KOSPI maintained a relatively steady trend in July (2.18%), January (2.12%), and December (1.82%).
Stock market experts cite seasonal factors as the reason behind September’s weakness. Analysts note that, as the end of the third quarter approaches, institutional investors are rebalancing their portfolios and selling to lock in gains or cut losses, a trend that coincides with a cluster of monetary policy events by the U.S. Federal Reserve (Fed).
The question is whether this seasonal pattern will repeat itself this year. Two main viewpoints are at odds within the securities industry. One view is that caution is warranted as uncertainty stemming from the Fed is on the rise, while the other is the “valuation recovery theory,” which argues that the current KOSPI price reflects an excessive discount, leaving room for a rebound.

In fact, uncertainty surrounding the Fed’s interest rate policy is emerging as a key variable this September. In his first Jackson Hole speech last weekend, Fed Chairman Kevin Warsh noted that there is no evidence of a meaningful improvement in core inflation, leaving the door open to a rate hike.
Lee Kyung-soo, an analyst at Hana Securities, noted, “This poured cold water on expectations of strong earnings from NVIDIA and weighed on the market.”
Also on the horizon is the release of U.S. employment data this week, which is expected to be the biggest factor in determining the future direction of interest rates. Given that the July nonfarm payrolls data—which showed a shocking decline of 23,000 jobs—was released last month, analysts explain that whether the job market recovers in August will determine the validity of the data supporting the September–October rate hike scenario hinted at by Chair Wash at Jackson Hole. He noted, “A sluggish job market could actually have a positive effect on the market.”
Some analysts also point out that it is difficult to predict the stock market trend for September this year based solely on historical averages. They explain that the scale of share buybacks by SamsungElectronics(005930)and SK hynix(000660)remains a variable that could curb foreign selling, and that the excessive discount relative to earnings forecasts is a factor supporting the lower end of stock market valuations.
In a report released today, Noh Dong-gil, an analyst at Shinhan Investment Securities, projected a KOSPI range of 6,600 to 8,000 points for September. He stated, “Applying an interest-rate-adjusted fair price-to-earnings (P/E) ratio of 8.5 times to the 12-month forward earnings per share (EPS) of 1,205.9 points yields a price of 10,250 points, which fully reflects the consensus,” and “The closing price of 6,789 points on the 28th represents a price that acknowledges only 66.2% of the consensus,” he noted.
He explained, “Even at 8,000 points, there remains a 22% discount relative to the consensus,” adding, “Of the 33.8% discount currently reflected in the price, only about one-third is expected to recover, while the remaining two-thirds are attributed to uncertainty surrounding next year’s earnings and the return on investment in artificial intelligence (AI).”
Share buybacks by SamsungElectronics and SK hynix are also key variables. Analyst Noh noted, “The two companies actually acquired 10.3 trillion won worth of their own shares between August 20 and 28, with a remaining planned purchase amount of 44.7 trillion won,” adding, “The market is not fully accounting for them as buyers capable of immediately filling the gap left by foreign investors.” In fact, the 8.05 trillion won acquired between the 24th and 28th is roughly equivalent to the 8.32 trillion won in net selling by foreign investors on the KOSPI during the same period.
He predicted, “The volatility index (VKOSPI) has fallen from 97 at the end of June to 50 at the end of August, and the burden of leveraged trading in individual stocks and portfolio rebalancing has also decreased compared to the peak,” adding, “As volatility declines, there is potential for long-term foreign capital—which had reduced its risk exposure—to re-enter the domestic stock market.”
There are also forecasts that if the U.S. Federal Open Market Committee (FOMC) decides to keep the benchmark interest rate unchanged on the 17th of next month (local time), the market could actually gain upward momentum.
Lee Kyung-min, an analyst at DaishinSecurities, said, “Although the probability of a rate hike in September has risen to the 60% range following the Jackson Hole Symposium, it is highly likely that the August core Consumer Price Index (CPI) will hit a new annual low of around 2.4%, so the Fed will likely opt to keep rates unchanged in September,” “September, which many investors view as a risk factor, could actually serve as a trigger to strengthen the upward momentum,” he added.
DaishinSecurities analyzed that, in light of this, the upper end of the KOSPI’s September trading range should be set between 8,500 and 9,300. The analyst noted, “The KOSPI’s forward P/E ratio remains at 5.63x, near historic lows, reflecting skepticism regarding next year’s earnings,” and predicted, “If September’s events help alleviate this skepticism, the index could rise to the 8,500–9,300 range, accompanied by a re-rating to a forward P/E ratio of 7–8x.”