[Edaily Reporter PARK MIN ] On the 31st, the KOSPI rebounded from a three-day plunge to close with a surge of over 17%, setting a new record for the largest single-day gain since the 2008 global financial crisis. On that day, the second-largest company by market capitalization, SK hynix(000660), rose to the intraday price limit, hitting the “upper limit,” while the largest, SamsungElectronics(005930), also soared, setting a new record with a 26% gain—its highest single-day increase ever.

This sharp rally is attributed to strong rebound buying following the recent excessive decline in stock prices, as well as a recovery in investor sentiment driven by a significant rise in semiconductor stocks on the New York Stock Exchange overnight.

◇Frenetic buying by foreign investors... KOSPI reclaims 6,500 mark

According to MP Doctor, as of 3:30 p.m. today, the KOSPI closed at 6,595.45, surging 1,001.89 points (17.91%) from the previous trading day and recording its “largest-ever single-day percentage gain.” Just three days after breaking below the 6,000 mark on the 28th—which had sent retail investors into a panic sell-off—the index recovered to the 6,500 level with its largest-ever single-day gain. Notably, today’s gain far surpassed the previous record set during the 2008 global financial crisis (11.95% based on closing prices).

Foreign investors’ buying momentum was particularly prominent in the stock market that day. Following net purchases of 1.3299 trillion won (according to KRX) in the KOSPI market the previous day, foreign investors drove the index higher by snapping up 7.1821 trillion won worth of shares—more than five times the previous day’s amount. This marks the largest single-day net purchase since the start of July. Following foreign investors, institutional investors also joined the net buying trend by purchasing 1.1783 trillion won, while retail investors recorded net sales of 8.2543 trillion won.

At the same time, the KOSDAQ closed at 719.76, up 74.98 points (11.63%) from the previous trading day. This marks a return to the 700-point level just three days after it had fallen below the 600-point mark. By investor type, institutions and foreign investors drove the index higher with net purchases of 296.2 billion won and 169.3 billion won, respectively. In contrast, retail investors recorded net sales of 468.7 billion won.

In particular, strong buying pressure flooded both the KOSPI and KOSDAQ markets immediately after the opening bell, triggering a series of “buy-side cars”—temporary suspensions of program trading.

◇SK hynix Soars 29.95% Intraday... Hits All-Time High

Large-cap semiconductor stocks were at the center of the rebound. SK hynix surged by more than 20% early in the session and reached 1,718,000 won—the upper price limit of 29.95%—around 2:10 p.m. It then maintained its sharp upward trend near the upper limit before closing at the upper limit just before the end of the regular session.

This marks the first time SK hynix has hit the upper price limit since April 14, 15, and 16, 2003, when it reached the then-15% upper limit following the resumption of trading after a stock split. In particular, this marks the first time in history that SK hynix has hit the intraday price limit since June 15, 2015, when the KOSPI market’s price limit range was expanded to ±30%.

SamsungElectronics, the company with the largest market capitalization, also closed at 262,500 won—up 26.81% from the previous day—setting a new record for its largest single-day percentage gain. In addition, the third-largest company, SKSQUARE(402340), and the fourth-largest, SamsungElectroMechanics(009150), both hit their daily upper price limits, while SAMSUNG C&T CORPORATION(028260)rose 19.56%, HyundaiMotor(005380)rose 10.54%, KIA CORPORATION(000270)rose 9.19%, HD HYUNDAI HEAVY INDUSTRIES(329180)rose 7.37%, and HANWHA AEROSPACE(012450)rose 6.01%.

Amid a market rally led by semiconductor stocks, KOSDAQ’s leading secondary battery stocks— ECOPRO CO., LTD(086520)—rose 12.04%, and ECOPRO BM CO., LTD.(247540)rose 7.25%, joining the upward trend. Rainbow Robotics(277810)surged 16.09%, JUSUNG ENGINEERING Co.,Ltd.(036930)soared 26.65%, WONIK IPS Co.,Ltd.(240810)rose 27.92%, and PSK INC.(319660)climbed 27.81%, driving the strength of the semiconductor materials, parts, and equipment sector.

By sector, technology stocks, led by semiconductors, drove the rally. The semiconductor and semiconductor equipment sectors surged 28.03%, recording the highest gain, while electronic equipment and devices (26.79%), electrical equipment (21.18%), conglomerates (16.75%), and life insurance (16.69%) also joined the rally. In contrast, domestic consumption sectors that had maintained their upward momentum the previous day—including tobacco (-3.61%), beverages (-1.47%), and credit cards (-0.74%)—posted losses as profit-taking selling pressure emerged.

◇Buyback on Oversold Conditions + Impact of New York Stock Market Rebound

Market observers attributed the day’s sharp rally to the fact that the recent stock price correction had been excessive, combined with the impact of semiconductors rising across the board on the New York Stock Exchange overnight. On the 30th (local time), the Philadelphia Semiconductor Index rose 8.19% on the New York Stock Exchange, and major semiconductor stocks such as Micron Technology (18.36%), SanDisk (25.99%), AMD (13.00%), and Intel (11.30%) posted double-digit gains.

In addition, SK hynix’s American Depositary Receipts (ADRs), listed in the U.S., surged 17.52%, recovering to their initial public offering price of $149. Analysts also note that the announcement the previous day (the 30th, Korea time) that SK Group Chairman Choi Tae-won had purchased 3,620 shares of SK hynix (worth 4.8 billion won) on the open market served as a trigger for the stock’s rebound.

Han Ji-young, an analyst at KIWOOM Securities, said, “Even with this sharp surge, the KOSPI’s monthly decline remains at around -22.1%, marking the third-largest monthly drop on record. It still remains in oversold territory and has fallen excessively.” She added, “It is important to note that confidence in the KOSPI’s overall earnings is recovering, driven by the earnings reports of hyperscalers, electronics, INICS Corporation, and other key sectors.”