On the 19th, the KOSPI and KOSDAQ indices are displayed on a large screen at the Hana Bank headquarters in Jung-gu, Seoul. On this day, the KOSPI closed at 9,052.42, down 11.42 points (0.13%) from the previous trading day, and the KOSDAQ closed at 966.59, down 34.34 points (3.43%). [Yonhap News] 

The KOSPI closed with a slight decline on the 19th due to a short-term surge and heightened uncertainty regarding the implementation of a ceasefire agreement between the US and Iran.

On this day, the KOSPI ended trading at 9,052.42, down 11.42 points (0.13%). This marks the first decline in seven trading days.

The index opened at 9,288.89, up 225.05 points (2.48%), and rose to a intraday high of 9,385.59 (+3.55%). However, it turned downwards around 12:37 PM, falling below the 9,000 mark and even dipping to 8,831.72 (-2.56%) at one point.

The intraday fluctuation range recorded on this day was 553.87, ranking as the fifth largest in history.

The total market capitalization of the domestic stock market surpassed 8,000 trillion won for the first time in the morning during the uptrend, but it decreased shortly after the KOSPI's reversal, closing in the 7,930 trillion won range.

Foreign investors, who led the "9,000-point rally" with net purchases of approximately 1.2 trillion won the previous day, shifted to net selling on this day, but the scale was limited to around 352 billion won.

Individual investors showed net purchases totaling 1.65 trillion won, but institutions increased their net selling in the afternoon, offloading 1.228 trillion won.

In the KOSPI 200 futures market, individuals and foreigners recorded net purchases of 226.5 billion won and 1.2364 trillion won respectively, while institutions posted net sales of 1.3827 trillion won.

As of 3:30 PM on this day, the won-dollar exchange rate in the Seoul foreign exchange market was 1,527.0 won, down 0.1 won from the previous trading day.

The primary factors influencing the KOSPI's intraday reversal are the recent short-term surge and the burden of concentration in the semiconductor sector.

Han Ji-young, an analyst at Kiwoom Securities, explained, "The dominant trend of a few sectors leading and the concentration phenomenon appear to be the fundamental reasons for today's decline. While expanding the allocation to semiconductors is rational, in the short term, there seems to be pressure from this concentration and profit-taking pressure after the KOSPI's surge of over 10% this week."

Indeed, on this day, only 115 KOSPI stocks rose, while a significant 787 stocks declined.

Adding to this, news emerged around lunchtime that the United States had postponed the scheduled departure of its delegation ahead of the signing of a Memorandum of Understanding (MOU) for a ceasefire agreement with Iran in Switzerland, which appears to have further dampened investor sentiment.

The White House announced that plans related to follow-up discussions on the nuclear negotiations with Iran had not been finalized, and US Vice President J.D. Vance would not be departing as planned. Reports also indicated that the Iranian delegation postponed their visit to Switzerland, citing Israel's attack on Lebanon.

However, the US negotiating team has stated that they are prepared to depart as soon as possible.

Seo Sang-young, an analyst at Mirae Asset Securities, commented, "Following the cancellation of the trip to Switzerland by US Vice President Vance, after Pakistan (the mediator) also canceled, and the announcement of the cancellation of related events in Switzerland, the market began to decline in earnest. US after-hours futures also fell."

He also pointed to concerns over US-China conflict as a factor for the decline, stating, "Concerns over US-China conflict also increased following reports that the US government suspects the influx of ASML equipment into China."

Samsung Electronics [005930] fell 2.34% to 354,000 won, and SK Hynix [000660] rose 2.94% to 2,764,000 won, respectively.

SK Hynix briefly reached "2.8 million Hynix" and surpassed a market capitalization of 2,000 trillion won on this day. However, its gain narrowed, and it closed with a market capitalization of 1,969 trillion 993 billion won.

The gains were largely led by top market capitalization stocks. SK Square [402340] (4.71%), Samsung Electro-Mechanics [009150] (3.18%), Hyundai Motor [005380] (2.00%), Samsung Life Insurance [032830] (5.97%), LG Energy Solution [373220] (1.12%), and Samsung C&T [028260] (1.24%) all rose. Samsung Electro-Mechanics briefly surged nearly 10%, setting a new 52-week high.

By sector, only Insurance (3.32%), Finance (1.04%), Electrical & Electronics (0.17%), and Transportation & Warehousing (0.05%) saw gains. All other sectors, except for Banking (unchanged), declined. Construction (-4.79%), Medical & Precision (4.29%), Electric & Gas (-3.38%), Pharmaceuticals (-3.14%), and General Services (-3.10%) experienced significant drops.

The KOSDAQ opened at 1,001.40, up 0.47 points (0.05%), but it surrendered the 1,000 mark again after six trading days, closing at 966.59, down 34.34 points (3.43%).

Individual and foreign investors recorded net purchases of 77.1 billion won and 487.3 billion won, respectively, but institutions' net selling of 584 billion won dragged down the index.

Among sectors, all were unchanged or declined except for Publishing & Media (5.00%). Non-metallic minerals (-5.12%) saw a decline of over 5%, followed by Machinery & Equipment (-4.69%), Transportation Equipment (-4.17%), Chemicals (-3.93%), and Technology Growth Businesses (-3.90%).

A total of 200 stocks rose, and 1,490 stocks declined.

The trading volume on the KOSPI and KOSDAQ markets on this day was 65.3318 trillion won and 10.6501 trillion won, respectively.

The total trading volume for the pre-market and main-market of the alternative trading exchange, NEXTRA, was 39.6179 trillion won.