On the 31st, the KOSPI surged more than 14% right after the open, setting a new record for the biggest single-day gain. Buy sidecars were triggered simultaneously on both the KOSPI and KOSDAQ markets.
That day, the KOSPI opened at 5,657.79, up 64.23 points (1.15%) from the previous trading day. The index quickly widened its gains right after the open, soaring to as high as 6,424.71 intraday. Maintaining strong momentum afterward, it was trading at 6,428.22 as of 9:33 a.m.
The KOSPI's gain that day ranks No. 1 on record. The previous highest single-day rise was Oct. 30, 2008, when a U.S.-Korea currency swap was signed, and the KOSPI jumped 11.95% in one day. It also broke the previous record on a points basis. The prior record was on June 9, when the KOSPI rose 612.52 points.
As the sharp rally continued right after the open, buy sidecars were triggered simultaneously on both markets. According to the Korea Exchange (KRX), a buy sidecar was triggered on the main board at 9:06:02 a.m. that day, and one second later, at 9:06:03 a.m., a buy sidecar was also activated on the KOSDAQ market.
Robust foreign buying is lifting the index. On the main board, foreigners are net buyers of 4.48 trillion won. In contrast, individuals and institutions are net sellers of 4 trillion won and 370 billion won, respectively.
Stocks are soaring, led by Samsung Electronics(005930) and SK hynix, which had fallen sharply recently. Samsung Electronics is up 21.74%, and SK hynix is up 25.95%. SK Square(402340), grouped as related to SK hynix, also jumped 29.91%, and Samsung Electro-Mechanics hit the upper price limit.
The surge in Korea's stock market that day is seen as reflecting the strength in semiconductor stocks on Wall Street overnight. U.S. stocks rose across the board, boosted by strong earnings from Microsoft (MS) and a sharp rally in chip stocks. As options buying and short covering poured into recently slumping chip names, tech led the index higher.
On the 30th (local time), the Dow Jones Industrial Average closed at 52,208.06, up 1.19% from the previous trading day. The Standard & Poor's (S&P) 500 rose 1.66% to 7,437.63, and the tech-heavy Nasdaq composite climbed 2.78% to 25,122.18.
MS beat market expectations on the back of growth in its Azure and artificial intelligence (AI) businesses. As concerns about a slowdown in AI investment eased, MS shares surged 15.51%. SanDisk and Micron also soared 25.99% and 18.36%, respectively.
The Philadelphia Semiconductor Index (SOX), which consists of 30 major chip stocks listed in the United States, jumped 8.19%. It was the biggest gain in about one year and three months since the 18.73% rise recorded on Apr. 9, 2025.
The American depositary receipt (ADR) of SK hynix listed in the United States also surged 17.52%, recovering its offer price of $149. The previous day, an announcement that Chey Tae-won, chairman of SK Group, bought 3,620 shares of SK hynix on the market for 4.8 billion won is also seen as a catalyst for the rebound.
Han Ji-young, a Kiwoom Securities researcher, said, "The recent plunge in chip stocks was significantly affected by forced selling from losses at leveraged funds," and noted, "We judge that deleveraging related to the liquidation of the Leopold fund has entered its later stage."
Han added, "The domestic market will also attempt a rebound, helped by expectations for the resolution of deleveraging in chip stocks and strength in KOSPI200 night futures."
The KOSDAQ is also showing strong gains. The KOSDAQ index opened at 666.47, up 21.69 points (3.36%) from the previous trading day. As chip stocks soar, Jusung Engineering(036930) is up 27.37%, Wonik IPS is up 24.64%, and PSK is up 28.80%, with semiconductor materials, parts, and equipment stocks surging across the board.