Daewoo E&C jumps 8.47%, Samsung Electro-Mechanics falls 5.78% as KOSPI slips 0.58%

1. Construction rose, chip components fell: a rotation day

The KOSPI climbed as high as 7,171 intraday, within reach of the 7,000 line, before retail profit-taking in the afternoon erased most of the gain.

The index closed at 6,954.52, down 40.87 points, or 0.58%, on September 8, 2026. According to Asia Economy Daily, foreign investors bought a net 648.2 billion won and institutions bought a net 642.8 billion won near the close, while retail investors sold a net 3.03 trillion won.

The split by stock was clear. Construction and power-related names led the gainers, while chip-component, battery and biotech stocks that had rallied hard in recent days fell together. The chart below shows that shape.

2. Daewoo E&C jumps 8.47% on a U.S. nuclear deal and Gadeokdo

The day’s biggest mover was Daewoo E&C, up 1,560 won, or 8.47%, to close at 19,970 won after trading as high as 21,300 won intraday.

Two catalysts stood out. According to Ajunews and EBN News, Korea and the U.S. are discussing building up to eight large nuclear reactors in the U.S. as a follow-on to the countries’ investment project, and Daewoo E&C, which has overseas nuclear construction experience, was named a likely beneficiary. Separately, a Daewoo E&C-led consortium submitted its basic design for the 10-trillion-won Gadeokdo New Airport project, with a review due next month, Job Post reported.

The stock also rose 9.26% in the previous session, putting the two-day gain near 18%. That makes today’s move look less like a one-day spike and more like a continuing story.

The construction sector index rose 2.72% on the day, but only 31 of its 78 constituents advanced while 36 fell, so the sector did not move as one. Daewoo E&C and Hyundai E&C, both carrying clear nuclear and overseas-order catalysts, did the heavy lifting.

3. Chip components, batteries and biotech fell together

The chip-related names that drove the KOSPI’s 4.61% jump the previous session mostly fell back today. The stocks that had risen the most also tended to fall the most.

Samsung Electro-Mechanics dropped 5.78%, the steepest decline among the core names we track. Foreign investors sold a net 216,806 shares and institutions a net 88,245 shares, putting both sides on the selling side. There was no specific negative disclosure; Jaekyung Ilbo attributed the move to profit-taking after a short, sharp run-up.

LG Energy Solution fell 3.86%, Kakao and Alteogen each fell 3.15%, and Rainbow Robotics fell 3.35%. All had risen sharply in recent sessions.

Even within chips, direction split. Jusung Engineering, a chip equipment maker, rose 3.95%. Namdo Ilbo reported that foreign investors bought a net 63.7 billion won of the stock, the most of any KOSDAQ name that day, on brokerage forecasts that next year’s operating profit could more than double to 130-150 billion won.

Components were sold. Equipment was bought.

4. Foreign investors sold some of the same names institutions bought

Doosan Enerbility rose 1.82%, but the flow behind it was unexpected. Foreign investors sold a net 226,972 shares while institutions bought a net 1,331,885 shares and drove the gain.

Hyundai E&C was similar. Foreign investors sold a net 146,735 shares, but institutions bought a net 618,921 shares, and the stock closed up 3.55%. Hyundai E&C also rose more than 6% the previous session, its second straight day of gains.

In both cases, institutions appear to have absorbed what foreign investors sold. That split suggests foreign and domestic institutional investors are not yet reading the nuclear and overseas-order story the same way.

5. Oil prices were also part of why the KOSPI gave back its gain

Edaily pointed to rising global uncertainty and concern over oil prices as part of why the index gave back its late-session gain.

Over the weekend, Saudi Arabia’s Aramco oil facilities came under attack and U.S.-Iran military tensions rose again, sending global crude to a six-week high, according to Financial News and the Korea Economic Daily. Renewed worry about a supply disruption weighs on inflation and rate expectations, which analysts cited as one reason retail investors rushed to lock in gains in the afternoon.

It’s a backdrop the index alone does not show.

6. The KOSDAQ fell further, and the won edged down

The KOSDAQ closed down 10.31 points, or 1.25%, at 811.88, a steeper decline than the KOSPI’s. The construction and power theme that lifted the KOSPI had no KOSDAQ equivalent, while growth names such as Alteogen and Rainbow Robotics fell together.

The won-dollar rate was quoted down 0.18% at 1,344.60 won (Hana Bank, 6:21 p.m.).

The currency’s direction tracks foreign flows. According to Newspim, foreign investors sold a net near 170 trillion won of KOSPI shares from May through August, then turned to buying in September. Today’s net buying extends that shift.

Today's Foreign Investor Flows

What to watch next session

First, the 7,000 line. The index reached 7,171 intraday before giving it back, so the tone at the next open will show how much weight that rally still carries.

Second, oil. If the Aramco attack and U.S.-Iran tensions escalate further, refiners and chemical names face more pressure and inflation expectations firm up; a de-escalation would ease that pressure.

Third, the pace of foreign and institutional buying. Whether September’s buying streak can keep absorbing retail profit-taking is the open question.

Fourth, the construction and nuclear theme. Seoul’s review of the Gadeokdo airport bid isn’t due until next month, but any earlier news on the U.S. nuclear talks could move Daewoo E&C, Hyundai E&C and Doosan Enerbility again.

What's worth watching today

The KOSPI’s decline today doesn’t mean foreign investors were selling. Asia Economy Daily reported foreign investors bought a net 648.2 billion won again today.

According to Newspim, foreign investors sold a net 44.05 trillion won of KOSPI shares in May, 45.07 trillion in June, 8.62 trillion in July and 9.79 trillion in August — net buyers in only two of the last eight months, with cumulative net selling approaching 170 trillion won.

The shift came after the KOSPI’s 4%-plus plunge on September 2. Foreign investors actually increased their buying from there, adding a net 1.1141 trillion won in the KOSPI cash market on September 7 alone, plus 1.7 trillion won through program (arbitrage) trading. Reports also pointed to increased call-option buying, which some read as more than simple bargain-hunting.

If investors who sold for five straight months have changed direction, whether that holds matters more than any single day’s index move.

Daewoo E&C’s 8.47% jump was backed by flow on both sides. Foreign investors bought a net 1,578,488 shares and institutions bought a net 1,598,921 shares, both buying heavily in the same direction.

Hyundai E&C and Doosan Enerbility, grouped in the same nuclear-and-construction theme, looked different. Hyundai E&C’s foreign investors sold a net 146,735 shares while institutions bought a net 618,921 shares, producing a 3.55% gain; Doosan Enerbility’s foreign investors sold a net 226,972 shares while institutions bought a net 1,331,885 shares, for a 1.82% gain.

A split like that reflects a split in conviction. Foreign investors moved with the crowd on Daewoo E&C, where the catalyst is concrete, but appear less convinced on names rising mainly on nuclear-deal hope.

Oil prices were also part of why the KOSPI gave back its late-session gain. Edaily cited rising global uncertainty and oil-price concern as part of the backdrop.

Over the weekend, Saudi Aramco’s oil facilities were attacked and U.S.-Iran military tensions rose again, according to Financial News and the Korea Economic Daily. WTI crude rose 1.8% to $93.10 a barrel and Brent rose 1.5% to $97.73, both six-week highs.

Korean refiners rallied in sympathy, the Korea Economic Daily reported. Higher oil prices weigh on import prices and rate expectations, a headwind that could keep pressing on growth names such as chips and batteries.

It’s not just today’s story — it carries into the next session too.

Sources

• Asia Economy Korean-language article
• Edaily Korean-language article
• Money Today Korean-language article
• Aju Business Daily Korean-language article
• EBN Korean-language article
• job-post.co.kr Korean-language article
• job-post.co.kr Korean-language article
• namdonews.com Korean-language article
• jkn.co.kr Korean-language article
• Financial News Korean-language article
• Korea Economic Daily Korean-language article
• Newspim Korean-language article