South Korea’s top 1% of stock traders by return — the “super high performers” — bought Samsung Electronics most heavily while selling SK Hynix the most in early trading on the 4th, as semiconductor mega-caps rebounded together. Profit-taking was also evident in semiconductor equipment stocks that had surged sharply.

According to Mirae Asset Securities, which tracked trades by its top 1% of clients by one-month return through 9:30 a.m. that day, Samsung Electronics was the No. 1 net buy. Samsung Electro-Mechanics, Alteogen, LG Electronics, and LG Innotek followed in the top net-buy rankings. Hyundai Mobis and LG CNS also newly entered the upper ranks.

The KOSPI opened up more than 1% and extended gains. A key driver was the easing of the surge in U.S. long-term Treasury yields after Federal Reserve Governor Christopher Waller said he could support holding the benchmark rate steady at the Federal Open Market Committee (FOMC) meeting on the 15th–16th if inflation data confirms easing price pressures. Overnight on Wall Street, the Dow Jones Industrial Average rose 1.2% and the Nasdaq Composite gained 1.4%, extending a two-day winning streak.

Samsung Electronics, the top net buy, traded at ₩254,000 (approximately $190), up ₩4,000 (1.60%) from the previous session. The stock had been dragged down on the 2nd when the KOSPI plunged 4% amid a spike in international oil prices and a shock from U.S. Treasury yields, so funds appear to have flowed back into mega-caps during the rebound. Samsung Electro-Mechanics rose 2.45% to rank second in net buying.

By contrast, the super high performers sold SK Hynix the most. SK Hynix traded at ₩1.63 million (approximately $1,200), up ₩34,000 (2.13%) — a larger gain than Samsung Electronics — but these elite traders chose to lock in profits on the stock. Selling to realize gains was also pronounced in semiconductor equipment stocks that had jumped more than 10%.

Foreign and Institutional Buying vs. Retail Selling

Across both main markets, retail investors were net sellers while foreign and institutional investors bought stocks, driving the indices higher. As of 10:44 a.m., the KOSPI stood at 6,647.68, up 68.20 points (1.04%) from the previous session. On the KOSPI market, retail investors sold a net ₩1.2792 trillion (approximately $942.3 million), while foreigners bought a net ₩262.2 billion (approximately $193.1 million) and institutions bought a net ₩597.1 billion (approximately $439.8 million).

At the same time, the KOSDAQ rose 11.34 points (1.44%) to 801.55, reclaiming the 800 level. On the KOSDAQ, foreigners bought a net ₩88.7 billion (approximately $65.3 million) and institutions bought a net ₩45.6 billion (approximately $33.6 million), while retail investors sold a net ₩122.5 billion (approximately $90.2 million).

A current account surplus driven by strong semiconductor exports also served as a catalyst for stock gains. According to preliminary balance-of-payments data released by the Bank of Korea, the July current account surplus reached $42.08 billion (approximately ₩57.1 trillion), the second-largest on a monthly basis ever and the largest for any July. An explosive surge in semiconductor exports widened the goods surplus, lifting the overall current account surplus.

Kim Seok-hwan, an analyst at Mirae Asset Securities, said: “The current account surplus was the second-largest on record, and semiconductor exports surged 176.3% year-over-year, lifting AI semiconductor-related stocks such as SK Hynix, Samsung Electronics, Hanmi Semiconductor, and EO Technics.”

Robotics Stocks Surge… Robotis Up 19%

On the KOSDAQ, strength in semiconductor and robotics stocks was particularly notable. Robotis traded at ₩295,000 (approximately $220), up ₩47,000 (18.91%) from the previous session. The stock surged more than 22% intraday, maintaining a strong upward trend throughout the morning. Rainbow Robotics rose 3.89%, Wonik IPS gained 5.52%, and EO Technics climbed 4.43%.

Kim noted: “China’s humanoid development rush has sharply increased Chinese revenue for South Korean component makers. Expectations for replacement demand for Chinese products in the North American market also lifted robotics stocks.”

Han Ji-young, an analyst at Kiwoom Securities, said: “The easing of the surge in the U.S. 10-year Treasury yield following Governor Waller’s dovish remarks, along with rotational buying centered on large-cap tech stocks such as NVIDIA (+1.8%), Tesla (+5.4%), and Microsoft (+2.9%), drove the market. Over time, South Korea’s supply-demand base should normalize, continuing a path of gradually rising lows.”

Kang Jin-hyeok, an analyst at Shinhan Securities, said: “The KOSPI rose more than 1% as investors relieved by the Fed governor’s signal of a September rate hold entered the market. The KOSDAQ rebounded after four sessions as buying flowed into growth stocks led by robotics names amid improving macroeconomic conditions.”

Super High Performers Take a Selective Approach Amid Short-Term Trading Surge

The trading patterns of the super high performers contrasted with the short-term trading trend spreading across the South Korean stock market. According to the Korea Exchange, SK Hynix’s average daily share turnover rate in August was 11.4%, more than 1.5 times higher than the same month a year earlier. Samsung Electronics’ turnover rate also rose 1.6 times over the same period, from 4.7% to 7.8%.

Securities industry observers attribute this to increased volatility in large-cap semiconductor stocks stimulating short-term trading demand, as no clear market leader has emerged in the South Korean stock market. Reasons cited for the KOSPI’s failure to break above the 7,000 level include long-term interest rate volatility, semiconductor supply-demand burdens, and elevated risk premiums following the July plunge.

Against this backdrop, the super high performers’ contrasting choices on Samsung Electronics and SK Hynix drew attention. Both are semiconductor mega-caps that rose together that day, but the elite traders appear to have bought Samsung Electronics on expectations of further upside while prioritizing profit-taking on SK Hynix after its sharp short-term surge.