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Weekly wrap · Week of Sep 21 – Sep 23, 2026 · 3 trading days

KOSPI gains 2.7% to 7,080.9 as Samsung Electronics jumps 9.4%; defense, shipbuilders and steel fall

KOSPI+2.7%KOSDAQ+2.1%KOSPI 200+3.3%

The main story was the memory-chip rally. KOSPI rose 2.7% to 7,080.9 over the three sessions and returned above 7,000. Samsung Electronics rose 9.4% as strong US chip stocks and record September chip exports supported it. Chips made up 47.8% of Korea's exports from September 1 to 20, and Yuanta Securities said the memory cycle would last longer rather than just slow in price gains. Samsung Electro-Mechanics rose 8.6% and SK Square rose 10.3%. SK hynix was nearly flat at +0.3%.

A second story was Meta's new AI agent, MUSE, which reached the top of the US App Store. Brokers said it lifted expectations for CPU and server demand and sentiment toward Korea's AI chip chain. Fadu, which supplies enterprise SSD controllers to Meta, rose 33.8%, and Eugene Investment & Securities raised its target price to ₩110,000 and expected a third-quarter earnings surprise. Chip testing and packaging rose 9.8%, with Exicon up 21.3%, Hana Micron up 19.5% and TSE up 18.9%. Oil prices settling and hopes for US-Iran talks were also cited as supportive, while defense, shipbuilding, construction and steel fell.

Why the market moved

KOSPI regained 7,000 as record September chip exports and strong US chip stocks lifted Samsung Electronics, with oil calming and Meta's MUSE adding AI sentiment. Gains narrowed before the holiday.123456

Top themes

Chip testing & packaging

Record chip exports and US chip strength123

  • Exicon, Chip testing and packaging, best in theme+21.34%
  • Hana Micron, Chip packaging name, rose 19.5%+19.53%
  • TSE, Chip testing and packaging name+18.94%

Semiconductor equipment & materials

Samsung Electronics surges as chip exports hit record and K…123

The big stories

Samsung Electronics surges as chip exports hit record and KOSPI reclaims 7,000

KOSPI closed up 2.72% and Samsung Electronics rose 9.38% as US chip-stock strength and record September chip exports lifted the index back above 7,000. Chips made up 47.8% of Korea's exports from September 1 to 20, and Yuanta Securities said the memory upcycle would last longer than a mere slowdown in price gains.12345

Directly affected

Next in line

Meta's AI agent MUSE lifts Korean AI chip and server supply chain

Meta's new AI agent MUSE reached the top of the US App Store, boosting expectations for CPU and server demand and lifting Korean AI chip stocks. Samsung Electro-Mechanics rose 8.57% and SK Square 10.29% in the same session.123

Directly affected

Next in line

Fadu soars on Meta-linked eSSD demand and upgraded target

Fadu, which supplies enterprise SSD controllers to Meta, closed up 33.77% as AI infrastructure demand lifted expectations. Eugene Investment & Securities expected a third-quarter earnings surprise and raised its target price to KRW 110,000.12

Directly affected

Next in line

Neosapience and Tomatosystem jump while KOSDAQ listings swing

Neosapience closed up 157.99% and Tomatosystem up 106.93% in KOSDAQ trading, while Orum Therapeutics fell 33.16%. Ingenia Therapeutics rose 32.10% on expectations for Phase 3 expansion of a Merck ophthalmic drug candidate.12345

Directly affected

Further out

Hyundai Steel falls nearly 11% with no disclosed cause

Hyundai Steel closed down 11.25% with no negative disclosure, according to a financial news report that cited broader investor caution and profit-taking. Dongkuk Steel Mill fell 8.75% the same session.1

Directly affected

Korea plans eight US reactors, with Westinghouse stake talks under way

The government is pursuing construction of eight large nuclear reactors in the US as a follow-up US investment project. Negotiations over a 5–10% stake in Westinghouse are ongoing, with the focus on the scope of Korea's business role.1

Directly affected

Next in line

The market

KOSPI closed at 7,080.92 (+2.7%), KOSDAQ at 844.48 (+2.1%) and KOSPI 200 at 1,126.12 (+3.3%). Breadth was weak: 1,168 stocks rose and 1,334 fell, with 262 unchanged. One report called the rally narrow and dependent on Samsung Electronics. Trading value was about ₩30.7 trillion, against an average of about ₩28.6 trillion. The index hit about 7,171 early on September 22 before giving back gains, with a holiday-related wait-and-see mood cited. The won strengthened 1.5% to 1,360 per dollar, the 3-year KTB yield was 4.006% (down 2.9bp) and the US 10-year yield was 5.11% (up 10.0bp).

KOSPIDaily closes · shaded: this wrap7,080.92
6,0007,0008,0009,000
Jun 15Jul 16Aug 21Sep 23
KOSDAQDaily closes · shaded: this wrap844.48
7008009001,000
Jun 15Jul 16Aug 21Sep 23

1,168 stocks rose, 1,334 fell · trading value ₩31T

USD/KRW1,360−1.5%
KTB 3y4.01-3bp
UST 10y5.11+10bp

Themes investors follow

Chip testing and packaging led at +9.8%, followed by semiconductor equipment and materials at +4.6%, HBM and AI chips at +4.4%, foundry and chip design at +3.3% and AI software at +3.2%. New Power Plasma rose 24.4%, Dawon Nexview 22.5% and Protec Mems Technology 22.1%. In AI software, Neosapience jumped 158.0% after listing on September 21 and then fell 13.1% and 19.4% on the next two days as profit-taking was cited. HT Robotics rose 29.0% though robotics overall was flat. Weak themes were zinc and non-ferrous metals (-5.5%), self-driving (-5.0%), hydrogen (-4.5%), shipbuilding (-3.8%), K-defense (-3.3%), construction (-3.3%) and steel (-3.0%). Hanwha Systems fell 7.6% and LIG Defense & Aerospace 7.0%. Korea plans eight large US reactors and is negotiating a 5-10% Westinghouse stake, yet Doosan Enerbility fell 3.8%. In biotech, Ingenia Therapeutics rose 32.1% on hopes for Phase 3 expansion of a Merck eye drug candidate, while Orum Therapeutics fell 33.2%.

Popular themes

Best themes

Worst themes

  • Zinc & non-ferrous metals−5.5%Daiyang Metal −15.7% · Youngpoong −8.7% · Poongsan −3.3%
  • Self-driving−5.0%StradVision −7.8% · HL Mando −5.6% · Nextchip −3.4%
  • Hydrogen−4.5%Doosan Fuel Cell −7.3% · Bumhan Fuel Cell −5.7% · Doosan Fuel Cell Pref. −3.9%
  • Shipbuilding−3.8%Hanwha Engine −7.2% · HD-Hyundai Marine Engine −6.7% · STX Engine −6.6%
  • K-defense−3.3%KP Aero Industries −8.1% · Hanwha Systems −7.6% · LIG Defense&Aerospace −7.0%
  • Construction & Middle East projects−3.3%Aptn −29.9% · Chinhung International 2nd Pref. −20.0% · Camus Engineering & Construction −8.8%

The biggest companies

Samsung Electronics (₩1,669.1 trillion market value) rose 9.4%. SK hynix (₩1,360.2 trillion) rose 0.3%. SK Square gained 10.3%, Samsung Electro-Mechanics 8.6%, Samsung C&T 4.6% and Samsung Life Insurance 3.9%. Down were LG Energy Solution (-3.4%), Hyundai Motor (-3.1%), Samsung Biologics (-2.3%), KB Financial Group (-1.0%), Hanwha Aerospace (-5.3%), Doosan Enerbility (-3.8%), HD Hyundai Heavy Industries (-4.1%), KIA (-5.3%) and Shinhan Financial Group (-0.7%). Hyundai Steel fell 11.3% with no negative filing; a report cited investor caution and profit-taking.

Who was buying and selling

Foreign investors were net sellers of about ₩419.1 billion on KOSPI and ₩201.3 billion on KOSDAQ. They bought Samsung Electronics (about ₩2.6 trillion), Samsung Electronics Pref., SK Square and Samsung Electro-Mechanics, and sold SK hynix (about ₩2.3 trillion), Doosan Enerbility, Hyundai Motor and Daewoo Engineering & Construction. Institutions bought Samsung Electronics (about ₩1.6 trillion), Samsung Electro-Mechanics and SK hynix, and sold NAVER, Doosan Enerbility and Samsung SDI. Retail investors sold Samsung Electronics (about ₩5.7 trillion) and SK hynix (about ₩1.2 trillion) and bought Doosan Enerbility, Hyundai Motor and NAVER.

Foreign investors

Net bought

  1. 1Samsung Electronics+₩2.6T+9.4%
  2. 2Samsung Electronics Pref.+₩277B+12.2%
  3. 3SK Square+₩243B+10.3%
  4. 4Samsung Electro-Mechanics+₩118B+8.6%
  5. 5LG Electronics+₩72B+5.3%
  6. 6Korean Air Lines+₩69B+7.5%
  7. 7Simmtech+₩54B+18.9%
  8. 8SK Innovation+₩53B+9.2%
  9. 9SFA Semicon+₩52B+17.2%
  10. 10Hana Micron+₩42B+19.5%
  11. 11GS Holdings+₩41B−2.8%
  12. 12S-Oil+₩34B+4.1%
  13. 13Isupetasys+₩33B+14.7%
  14. 14Hyosung Heavy Industries+₩32B−0.6%
  15. 15Tesco+₩30B+17.2%

Net sold

  1. 1SK hynix−₩2.3T+0.3%
  2. 2Doosan Enerbility−₩206B−3.8%
  3. 3Hyundai Motor−₩131B−3.1%
  4. 4Daewoo Engineering & Construction−₩93B−7.8%
  5. 5Taihan Fiberoptics−₩82B−3.4%
  6. 6Hanwha Aerospace−₩77B−5.3%
  7. 7KB Financial Group−₩63B−1.0%
  8. 8Leeno Industrial−₩61B+6.8%
  9. 9Taihan Cable & Solution−₩59B−1.6%
  10. 10Hanwha Systems−₩58B−7.6%
  11. 11Hyundai Engineering & Construction−₩50B−3.0%
  12. 12Samsung E&A−₩49B−4.7%
  13. 13Hanwha Ocean−₩48B−4.0%
  14. 14Samsung Heavy Industries−₩43B−2.6%
  15. 15Doosan−₩40B+4.5%

Institutions

Net bought

  1. 1Samsung Electronics+₩1.6T+9.4%
  2. 2Samsung Electro-Mechanics+₩300B+8.6%
  3. 3SK hynix+₩115B+0.3%
  4. 4SK Square+₩105B+10.3%
  5. 5LG Electronics+₩72B+5.3%
  6. 6KB Financial Group+₩67B−1.0%
  7. 7Korean Air Lines+₩60B+7.5%
  8. 8Isupetasys+₩54B+14.7%
  9. 9SK+₩50B+12.1%
  10. 10Doosan+₩42B+4.5%
  11. 11Shinhan Financial Group+₩31B−0.7%
  12. 12Daeduck Electronics+₩30B+15.7%
  13. 13Hana Financial Group+₩29B0.0%
  14. 14Iljin Electric+₩27B+6.7%
  15. 15ISC+₩25B+14.1%

Net sold

  1. 1NAVER−₩109B−1.5%
  2. 2Doosan Enerbility−₩96B−3.8%
  3. 3Samsung SDI−₩90B−3.7%
  4. 4Samyang Foods−₩56B−6.5%
  5. 5Hyundai Motor−₩51B−3.1%
  6. 6HD Hyundai Heavy Industries−₩47B−4.1%
  7. 7LG Energy Solution−₩43B−3.4%
  8. 8GS Holdings−₩41B−2.8%
  9. 9Hyundai Engineering & Construction−₩41B−3.0%
  10. 10KIA−₩39B−5.3%
  11. 11Samsung Electronics Pref.−₩39B+12.2%
  12. 12SK Telecom−₩38B−2.4%
  13. 13Silicon 2−₩33B−6.7%
  14. 14Daewoo Engineering & Construction−₩30B−7.8%
  15. 15SFA Semicon−₩29B+17.2%

Retail investors

Net bought

  1. 1Doosan Enerbility+₩298B−3.8%
  2. 2Hyundai Motor+₩178B−3.1%
  3. 3NAVER+₩135B−1.5%
  4. 4Daewoo Engineering & Construction+₩122B−7.8%
  5. 5Samsung SDI+₩122B−3.7%
  6. 6Hyundai Engineering & Construction+₩91B−3.0%
  7. 7Taihan Fiberoptics+₩79B−3.4%
  8. 8LG Energy Solution+₩76B−3.4%
  9. 9Hanwha Ocean+₩73B−4.0%
  10. 10Hanwha Aerospace+₩72B−5.3%
  11. 11KIA+₩72B−5.3%
  12. 12Taihan Cable & Solution+₩65B−1.6%
  13. 13Samsung Heavy Industries+₩57B−2.6%
  14. 14Neosapience+₩51B+158.0%
  15. 15HYBE+₩51B−5.5%

Net sold

  1. 1Samsung Electronics−₩5.7T+9.4%
  2. 2SK hynix−₩1.2T+0.3%
  3. 3Samsung Electro-Mechanics−₩415B+8.6%
  4. 4SK Square−₩343B+10.3%
  5. 5Samsung Electronics Pref.−₩236B+12.2%
  6. 6LG Electronics−₩147B+5.3%
  7. 7Korean Air Lines−₩127B+7.5%
  8. 8Isupetasys−₩86B+14.7%
  9. 9SK Innovation−₩67B+9.2%
  10. 10Hana Micron−₩55B+19.5%
  11. 11Simmtech−₩55B+18.9%
  12. 12Daeduck Electronics−₩45B+15.7%
  13. 13SK−₩43B+12.1%
  14. 14Samsung Securities−₩40B+6.8%
  15. 15DI−₩34B+17.0%

ETFs

Semiconductor ETFs led: HANARO Semiconductor Core Process Leaders rose 13.0%, KODEX US CPU Semiconductor TOP10 11.9%, PLUS AI Semiconductor Parts Materials Active 10.4% and SOL Semiconductor Back-End Process 10.1%. The weakest were KODEX WTI Crude Oil Futures (H) at -6.5%, KODEX Defense TOP10 at -5.9%, TIGER K Defense & Space at -5.9% and PLUS K Defense at -5.7%. Nuclear, Hyundai Motor Group, construction, shipbuilding and auto ETFs also fell 3.7% to 4.8%, so money moved toward chips and away from defense, nuclear and shipbuilding.

Best ETFs

Worst ETFs

Leveraged and inverse ETFs are left out; moves are the daily moves compounded.

How our signals did

No Squeeze! setups were recorded. Of 40 technical events, 21 worked. Tomatosystem's breakout (+18.9%), Samkee Energy Solutions' breakout (+20.9%) and Hanyang Digitech's breakout (+14.5%) worked, as did the downside calls on Orum Therapeutics and HD Construction Equipment. Korean Air Lines' 52-week high (-15.8%), Hana Micron's breakout (-17.6%), Soulbrain's breakout (-18.1%) and TLB's breakout (-15.7%) did not. No pair trades were flagged. Short squeeze scores were 60 for Meritz Financial Group, Hanssem and ISU Specialty Chemical, 58 for SM Entertainment and KMW. Neosapience listed up 243% on day one and Wise Planet rose 285.8%.

Notable technical signals

40 notable signals: 21 moved the way they pointed so far.

Highest short squeeze scores

Signals describe past prices. Results run from the signal to the latest close; they are not recommendations.

Written by AI from JONBUR's data and checked against those figures. Index and stock moves are the daily moves compounded over the period. Reasons come only from the linked daily wraps, news, filings and broker reports; when none gives a reason, we say so. Not financial advice.

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