South Korea's benchmark stock index opened sharply lower Thursday on overnight Wall Street tech losses and reports of allergy cases related to the vaccinations in Britain.

The Korea Composite Stock Price Index fell 26.77 points, or 0.97 percent, to 2,728.7 in the first 15 minutes of trading.

The fall was led by shares of tech giants, tracking a 1.94 percent overnight plunge on the Nasdaq composite. The US Federal Trade Commission's antitrust lawsuit against Facebook dropped investor appetite for tech heavyweights.

Overnight, the tech-heavy Nasdaq dipped 1.94 percent to 12,338.95 points. The Dow Jones Industrial Average retreated 0.58 percent, with the S&P 500 losing 0.79 percent.

Two allergic reactions observed in the British COVID-19 mass vaccination also drove down investor sentiment.

Market behemoth Samsung Electronics dropped 1.49 percent, and No. 2 chipmaker SK hynix shed 2.49 percent.

Chemical firm LG Chem lost 1.56 percent, and rechargeable battery maker Samsung SDI fell 1.41 percent.

Pharmaceutical giant Samsung Biologics retreated 0.61 percent, while Celltrion moved up 0.42 percent.

Internet giant Naver shed 0.87 percent, with its rival Kakao declining 1.33 percent.

Top automaker Hyundai Motor retreated 0.52 percent.

The local currency was trading at 1,086.0 won against the US dollar, down 1.2 won from the previous session's close. (Yonhap)