KOSPI Slides on Tech Volatility as KOSDAQ Gains; Samsung Electro-Mechanics Rebounds

The KOSPI fell 3.36% to 6,373.77 amid mixed signals from the tech sector, while the KOSDAQ rose 2.82% to 740.09. The won weakened to 1,438.20 per dollar. Today's session saw sharp divergences, with AI-related and earnings-driven stocks surging despite broader index weakness.

SamsungElectroMechanics (009150) +8.23%

Samsung Electro-Mechanics jumped 8.23% after a volatile period triggered by its Q2 earnings surprise. The company's AI-related sales drove strong results [3], but initial market reaction was negative, with shares plunging over 10% intraday on July 30 due to semiconductor investment sentiment weakening [2][6]. The stock then hit the daily upper limit on July 31, buoyed by a rally in New York semiconductor stocks [4]. Subsequent sessions saw continued strength, with a 6% gain on August 3 as the Q2 performance was digested [5]. Despite the rally, analysts lowered target prices, and the P/E remains high at 135.62 [1].

COSMO ROBOTICS CO., Ltd (439960) +13.16%

COSMO ROBOTICS jumped 13.16% as domestic robot stocks outperformed sharply, even as the KOSPI plunged nearly 5% [7]. The move was supported by a positive investment analysis report published on July 31, which likely spurred buying interest [8]. While some peers like Rainbow Robotics showed weakness, the broader robot sector demonstrated resilience, attracting investors seeking differentiation from the broader market sell-off. The company's fundamentals remain weak, with negative earnings and a P/B of 31.79, suggesting speculative momentum.

HYOSUNG HEAVY INDUSTRIES (298040) +7.61%

Hyosung Heavy Industries gained 7.61%, extending a sharp rebound. The stock rallied up to 25% intraday on July 31 as AI-related investment sentiment recovered, lifting power equipment stocks [9][13]. New order expectations added to the momentum [11]. A securities firm report on August 2 highlighted healthy earnings and set a target price of 3.4 million won, providing further support [12]. This came after a brief dip on July 30 due to concerns over hawkish US signals despite a rate freeze [14]. The company shows a strong ROE of 23.16% but a high debt ratio of 209.68%.

DaeduckElectronics (353200) +8.06%

Daeduck Electronics climbed 8.06% following an extreme earnings surprise. Q2 operating profit surged over 3,600% year-on-year to 70.3 billion won, driven by memory, FC-BGA, and MLB growth axes [16][17][19]. The stock hit the daily upper limit on July 31 along with other semiconductor substrate makers [15]. Analysts noted the company remains undervalued despite upward earnings revisions, with a focus on its mid-to-long-term roadmap for the second half [16][20]. The strong results and sector momentum overshadowed a high P/E of 113.2.

DaewooEngineering&Construction (047040) +7.51%

Daewoo E&C advanced 7.51%, rebounding sharply after a previous session's decline. The key catalyst was a 241.38 billion won construction contract disclosure, equivalent to 3% of revenue, which raised growth expectations [25]. Foreign and institutional investors simultaneously net purchased the stock, driving the price up over 12% intraday on July 31 [22]. The stock had fallen the day before on sector-wide concerns [23], but the contract news and low valuation—P/B of 1.69—likely attracted bargain hunting. The company carries a high debt ratio of 277.67% and negative earnings, warranting caution.

Sources

1. 삼성전기, 어닝 서프에 '상한가' 직행한 날…증권사는 TP 하향 조정 — 연합인포맥스 · 2026-07-31
2. '어닝 서프라이즈'에도…삼성전기 장중 10% 넘게 폭락 — 한국경제 · 2026-07-30
3. AI 관련 매출에 호실적 삼성전기, 주가 14% 넘게 급락 - 머니투데이 — mt.co.kr · 2026-07-30
4. 삼성전기 모처럼 상한가...뉴욕증시 반도체 업종 급등 — thecommoditiesnews.com · 2026-07-31
5. [특징주] 삼성전기, 2분기 호실적 영향.. 6%대 '강세' - g-enews.com — g-enews.com · 2026-08-03
6. [오늘의 주목주] '반도체 투심 위축' 삼성전기 주가 14%대 내려, 코스피 개인 매도세에 5590선 하락 마감 — 비즈니스포스트 · 2026-07-30
7. 코스모로보틱스 레인보우로보틱스 등 국내 로봇주, 일부 약세에도 주가 전반적 강세…코스피 5% 가까이 급락 속 차별화 — CBC뉴스 · 2026-08-03
8. 코스모로보틱스 투자분석 2026. 07. 31 — 주달 · 2026-07-31
9. 효성중공업 주가 장중 25%대 올라, AI 관련 투심 회복에 전력기기주 강세 — 비즈니스포스트 · 2026-07-31
10. 7월 마지막 주 효성중공업 주가 급반등 — 톱스타뉴스 · 2026-08-01
11. [특징주] 효성중공업, "신규 수주 기대".. 6%대 '강세' - g-enews.com — g-enews.com · 2026-08-03
12. [모닝 리포트] "효성중공업, 건강한 실적 숨 고르기에 목표가 340만원" — 뉴스핌 · 2026-08-02
13. [특징주] 돌아온 반도체 투심에 전력주도 강세…효성중공업·LS ELECTRIC 20%대 급등 — v.daum.net · 2026-07-31
14. 효성중공업 주가 장중 2%대 하락…미국 금리 동결에도 ‘강성 시그널’ 부담 — CBC뉴스 · 2026-07-30
15. [특징주] 반도체 기판株 강세…대덕전자·심텍 '상한가' — 뉴스핌 · 2026-07-31
16. 대덕전자, '메모리·FC-BGA에 MLB까지' 3대 축 성장성 확고…"실적 상향에도 현저한 저평가" — 프라임경제 · 2026-08-02
17. [잠정실적]대덕전자, 올해 2Q 영업이익 703억원, 전년동기比 3,658%↑... 영업이익률 대폭 개선 (연결) — 씽크풀 AI · 2026-07-31
18. 대덕전자1우 투자분석 2026. 07. 30 — 주달 · 2026-07-30
19. 대덕전자, 2026년 2분기 영업이익 702억7600만원…전년동기 대비 3666% 급증 — 디지털투데이 · 2026-07-31
20. [애널픽] "'어닝 서프' 대덕전자, 하반기 중장기 로드맵 주목" — 뷰어스 · 2026-08-03
21. 대우건설 주가, 7월 31일 장중 12,690원 13.30% 상승 — 톱스타뉴스 · 2026-07-31
22. [장중수급포착] 대우건설, 외국인/기관 동시 순매수… 주가 +12.32% — 뉴스핌 · 2026-07-31
23. [특징주] 대우건설, 공급계약에도 장중 하락…건설업종 부진 우려 : 기업주식정보 — 재경일보 · 2026-07-30
24. 7월 마지막 주 대우건설 주가, 급락 후 반등 마감 — 톱스타뉴스 · 2026-08-01
25. 대우건설 수주공시 - 22-대미-00시설공사(5004) 2,413.8억원 (매출액대비 3.00 %) — 한국경제 · 2026-07-31
26. 대우건설 주가 상승 중 — 아시아뉴스통신 · 2026-08-03

This is market commentary, not investment advice.