KOSPI and KOSDAQ Plunge Amid Massive Foreign and Institutional Sell-Off

The South Korean stock market experienced a sharp decline on September 14, 2026, with the KOSPI falling 3.26% to close at 6,684.37 and the KOSDAQ dropping 1.69% to 806.79. Market sentiment was heavily weighed down by substantial net-selling from both foreign and institutional investors, who offloaded 3.29 trillion KRW and 1.16 trillion KRW on the KOSPI respectively. The USD/KRW exchange rate finished the session at 1,343.03.

LIGHTRON FIBER-OPTIC DEVICES (069540) +11.76%

LIGHTRON FIBER-OPTIC DEVICES chart

Price now₩4,330
Prev close₩3,870
Change+11.89%
Mkt cap₩488B
P/E-11.39
P/B4.57
EPS₩-380
ROE-17.45%
Debt ratio24.44%
52W range₩592–8,100

Lightron Fiber-Optic Devices (069540) closed up 11.76% on the KOSDAQ. During the trading session on September 14, 2026, the stock climbed 5.43% to reach 4,080 KRW [1]. Despite this notable upward movement in intraday trading, the specific business drivers, corporate developments, or broader market factors behind the rise could not be confirmed from the available headlines [1]. The company currently holds a market capitalization of 0.49 trillion KRW.

AUK (017900) +30.00%

AUK chart

Price now₩10,270
Prev close₩7,900
Change+30.00%
Mkt cap₩595B
P/E140.68
P/B2.15
EPS₩73
ROE4.61%
Debt ratio8.44%
52W range₩1,760–22,450

AUK (017900) surged by the daily limit of 30.00% to close on the KOSPI. The sharp rise was primarily driven by strong market expectations surrounding artificial intelligence (AI) components [7]. Additionally, amid weakness in tech giant Samsung Electronics, KOSPI trading volume shifted away from large-cap stocks and concentrated on individual names like AUK [4]. The stock triggered a volatility interruption (VI) early in the session [3] and rose 19.11% to 9,410 KRW intraday [5]. Other specific business achievements or detailed reasons for the surge remain unconfirmed [2, 6].

FOOSUNG CO.,LTD (093370) +9.54%

FOOSUNG CO.,LTD chart

Price now₩14,680
Prev close₩13,310
Change+10.29%
Mkt cap₩1.6T
P/E293.6
P/B4.71
EPS₩50
ROE10.97%
Debt ratio110.71%
52W range₩5,700–23,550

Foosung Co.,Ltd (093370) gained 9.54%, supported by institutional investors who extended their net-buying streak to eight consecutive days [8]. The stock stabilized in the 13,000 KRW range [9, 11] and rose 4.21% to 13,870 KRW during intraday trading on September 14, 2026 [10]. However, the specific corporate developments or market factors driving this sustained upward momentum and institutional interest remain unconfirmed from the available reports [9, 10, 11, 12].

TMC (217590) +15.44%

TMC chart

Price now₩12,550
Prev close₩10,880
Change+15.35%
Mkt cap₩302B
P/E-570.45
P/B2.7
EPS₩-22
ROE1.97%
Debt ratio103.12%
52W range₩8,820–38,700

TMC (217590) advanced 15.44% on the KOSPI. The stock demonstrated a strong upward trend, rising to 12,680 KRW on September 14, 2026 [13], even as both major South Korean indices suffered heavy losses [14]. This rapid price movement triggered two separate volatility interruptions (VI) during the trading session [14]. The precise underlying catalysts or business developments driving this sharp divergence from the broader market's bearish tone remain unconfirmed.

BH (090460) +5.10%

BH chart

Price now₩19,990
Prev close₩19,020
Change+5.10%
Mkt cap₩674B
P/E22.06
P/B0.87
EPS₩906
ROE11.35%
Debt ratio71.32%
52W range₩12,440–43,400

BH (090460) rose 5.10% on the KOSPI. The primary driver of the stock's gains was Apple's unveiling of its first foldable phone [16, 17, 18]. This product launch fueled investor optimism that BH would benefit significantly from entering the foldable phone supply chain [15, 17, 18, 20]. General market expectations surrounding Apple's new iPhone lineup also contributed positively to the stock's upward movement [19], leading to an intraday gain of over 7% [15, 20].

Sources

  1. 빛과전자 주가, 9월 14일 장중 4,080원 5.43% 상승 — 톱스타뉴스 · 2026-09-14
  2. 광전자 주가, 상한가... 무슨 회사길래? — 금강일보 · 2026-09-14
  3. [속보] 광전자 VI 발동, 주가 장초반부터 급등 — CBC뉴스 · 2026-09-14
  4. [EBN 데이터센터] 삼성전자 약세 속 광전자 급등...코스피 거래대금은 대형주·거래량은 개별주 집중 — ebn.co.kr · 2026-09-14
  5. 광전자 주가, 9월 14일 장중 9,410원 19.11% 상승 — 중앙이코노미뉴스 · 2026-09-14
  6. 광전자, 상한가 진입.. +30.00% ↑ — 서울경제 · 2026-09-14
  7. [급등락주 짚어보기] 광전자·영풍, AI 부품 기대에 ‘上’ — 이투데이 · 2026-09-14
  8. [장중수급포착] 후성, 기관 8일 연속 순매수행진... 주가 +2.70% — newspim.com · 2026-09-14
  9. 후성 주가, 9월 11일 13,310원 0.53% 상승 마감 — 톱스타뉴스 · 2026-09-11
  10. 후성 주가, 9월 14일 장중 13,870원 4.21% 상승 — 톱스타뉴스 · 2026-09-14
  11. 9월 2주차 후성 주가, 1만3천원대 안착하며 상승 마감 — 톱스타뉴스 · 2026-09-12
  12. 후성 투자분석 2026. 09. 11 — 주달 · 2026-09-11
  13. 티엠씨 주가, 9월 14일 12,680원 16.54% 상승 — 톱스타뉴스 · 2026-09-14
  14. [속보] 티엠씨 VI 두차례 발동, 양대지수 하락 속 주가 급등 — CBC뉴스 · 2026-09-14
  15. 비에이치 주가 장중 7%대 상승, '애플 폴더블폰' 수혜 기대감 반영 — businesspost.co.kr · 2026-09-14
  16. [특징주] 비에이치, 애플 폴더블폰 공개로 두각.. 6%대 '강세' — 글로벌이코노믹 · 2026-09-14
  17. 애플 폴더블폰 공개에 수혜 기대감…비에이치 7% 강세 — 뉴시스 · 2026-09-14
  18. [특징주] 애플 첫 폴더블폰 공개…비에이치 수혜 기대감에 6% 상승 - 조선비즈 — Chosunbiz · 2026-09-14
  19. 아이폰 신제품 기대감에도 관련주는 희비…영풍·비에이치 주가 '룰루랄라' — 핀포인트뉴스 · 2026-09-14
  20. [핫타임] 비에이치, 애플 폴더블폰 수혜 기대에 7%대 강세 — v.daum.net · 2026-09-14

This is market commentary, not investment advice.