[Edaily Reporter Park Sun-Yeop ] The KOSPI plunged more than 5%, retreating to the 8,400 level. Amid continued selling by both foreign and institutional investors, a flood of sell orders—particularly in large-cap semiconductor stocks—triggered a series of intraday sell-side circuit breakers and general circuit breakers.
According to MP Doctor on the 26th, the KOSPI closed at 8,411.21, down 519.09 points (5.81%) from the previous trading day. The index showed weakness from the start of the session, then extended its losses, briefly falling as low as 8,126.84. Trading was temporarily suspended after the first-stage circuit breaker was triggered, and the index closed after partially recovering from its losses following the resumption of trading.

Earlier in the day, a sell-side “sidecar” mechanism was triggered in the KOSPI market. At 11:12:12 a.m., the Korea Exchange suspended the validity of program sell orders on the stock market for five minutes after the KOSPI 200 futures price remained more than 5% below the benchmark price for over one minute.
Subsequently, at 12:10:12 p.m., the first-stage circuit breaker was triggered. This measure was taken after the KOSPI index remained down by more than 8% from the previous day’s closing level for one minute, resulting in a 20-minute suspension of trading on the KOSPI market. This marks the fifth time a KOSPI circuit breaker has been triggered this year. It is the 11th time in history, and with the trigger occurring just three days after the previous one on the 23rd, it indicates that volatility in the domestic stock market has escalated dramatically.
In terms of supply and demand, foreign and institutional investors led the index lower with net sales of 4.6265 trillion won and 3.7845 trillion won, respectively. In contrast, retail investors absorbed the selling pressure with net purchases of 8.1914 trillion won. Program trading, combining arbitrage and non-arbitrage transactions, showed a net selling position of 3.9154 trillion won.
Securities analysts attributed the sell-off in major semiconductor stocks to concerns over slowing demand amid soaring memory prices, which came amid continued outflows of foreign capital. They explained that downward pressure spread across the broader market as profit-taking selling concentrated on semiconductor stocks, which had recently led the index’s rebound.
Lee Kyung-min, an analyst at DaishinSecurities, said, “Yesterday, Apple announced that demand for memory semiconductors had surged abnormally due to the expansion of its artificial intelligence (AI) data centers, and it raised prices for major products such as Macs and iPads to reflect the resulting cost burden.” He added, “In addition, news emerged that OpenAI may postpone its initial public offering (IPO) until next year as it struggles to secure investment demand at a valuation of around 1 trillion dollars.”
The analyst explained, “Concerns arose that the sharp rise in memory prices would lead to cost burdens for hyperscalers, which could ultimately result in a slowdown in demand for memory semiconductors.” He added, “At the same time, investor sentiment rapidly deteriorated as doubts spread regarding the valuations and investment demand for AI-related companies.”
He continued, “Large-cap semiconductor stocks, which had surged on the back of Micron’s strong earnings, reversed course and plummeted, leading the index lower,” adding, “As market leaders faltered, risk aversion spread across all sectors, resulting in panic selling across the board.”
Han Ji-young, an analyst at KIWOOM Securities, also cited concerns over declining memory demand, short-term profit-taking, and the negative effects of herd behavior as the reasons behind the day’s sharp decline. Han noted, “The sharp drop in Apple’s stock price stoked fears of a contraction in end-user demand following news of product price hikes driven by rising memory prices,” adding, “There is growing speculation that not only consumer goods companies like Apple but also hyperscalers may find it difficult to absorb rising memory prices, which could dampen their willingness to invest in capital equipment.”
He further explained, “While the KOSPI rebounded sharply by about 8.9% over the past two trading days, the semiconductor sector was the sole outperformer; today, however, profit-taking emerged within that sector.” He added, “As passive fund flows—which had been allocated to semiconductors—also withdrew, selling pressure spread across most sectors.”
However, one analyst assessed, “Concerns over a decline in memory demand are somewhat exaggerated,” noting, “In reality, the concentration of trading and the resulting increase in supply-demand volatility account for a significant portion of today’s sharp decline.” He added, “Although the high daily volatility is causing considerable fatigue, I maintain my previous view that prioritizing a holding strategy is appropriate at this point.”
By market capitalization, large-cap stocks fell 6.00%. Mid-cap and small-cap stocks also declined by 3.13% and 2.36%, respectively.
By sector, securities posted the largest decline, falling 6.61%. The electrical/electronics and machinery/equipment sectors also fell by 6.47% and 6.44%, respectively. In contrast, the medical/precision instruments sector rose 0.92%, showing relative strength.
Top-market-cap stocks also showed a generally weak performance. SamsungElectronics(005930)closed at 339,500 won, down 19,000 won (5.30%) from the previous trading day. SK hynix(000660)also closed at 2,673,000 won, down 244,000 won (8.36%).
In addition, SKSQUARE(402340)(-9.43%), LG Energy Solution(373220)(-5.82%), SAMSUNG C&T CORPORATION(028260)(-4.72%), HyundaiMotor(005380)(-4.47%), Samsung Life Insurance(032830)(-3.24%), and SamsungElectroMechanics(009150)(-0.20%) also posted losses.
Trading volume on the KOSPI market that day totaled 508.9 million shares, with a total trading value of 51.4875 trillion won. Including four stocks that hit their upper price limit, 111 stocks rose, while 780 fell. Two stocks hit their lower price limit, and 24 remained unchanged.
The KOSDAQ index also showed weakness, hitting a year-to-date low during the session. The KOSDAQ index closed at 851.37, down 36.44 points (4.10%) from the previous trading day. After extending its losses early in the session, the index fell to a year-to-date low of 838.53 before rebounding to partially offset the decline.
In the KOSDAQ market, retail investors were net sellers of 6684억원 worth of stocks. In contrast, foreign and institutional investors were net buyers of 3511억원 and 3081억원 worth of stocks, respectively. Program trading, combining arbitrage and non-arbitrage transactions, showed a net buying position of 3645억원.
Among the top market-cap stocks, Alteogen Inc.(196170)(-8.40%), ECOPRO BM CO., LTD.(247540)(-7.15%), Rainbow Robotics(277810)(-6.98%), and ECOPRO CO., LTD(086520)(-6.47%) all posted losses. Major growth stocks—including biotech, secondary batteries, and robotics—performed poorly across the board, exacerbating the decline in the KOSDAQ index.