Seoul shares ended sharply lower Wednesday, breaking their four-day winning streak, as the downgrade of the US credit rating stoked investors' concerns. The South Korean won declined against the US dollar.

The benchmark Korea Composite Stock Price Index retreated 1.9 percent, or 50.6 points, to 2,616.47. Trading volume was heavy at 694.5 million shares worth 15.7 trillion won ($12.1 billion), with decliners outnumbering gainers 652 to 230.

The tech-heavy Kosdaq dropped more than 3 percent.

Wall Street finished mixed Tuesday as investors took a breather from a monthslong rally ahead of earnings reports from major companies, including Apple Inc. and Amazon.com Inc., and US jobs data.

The Dow Jones Industrial Average gained 0.2 percent, while the tech-heavy Nasdaq Composite trimmed 0.43 percent and the S&P 500 lost 0.27 percent.

Fitch Ratings downgraded the credit rating of the United States to AA+ from AAA, citing "repeated debt limit standoffs and last-minute resolutions."

"Investors' appetite went sharply down in Asian stock markets in the aftermath of the downgrade of the US credit rating by Fitch," Kim Seok-hwan, an analyst at Mirae Asset Securities Co., said.

Kim said big-cap shares led the decline in the Kospi, especially stocks related to secondary battery and semiconductor, on profit-taking.

Foreign investors and institutions sold off shares worth 84.5 billion won and 686.6 billion won, respectively, while retail investors bought a total of 772.2 billion won worth of shares.

In Seoul, most big-cap stocks logged big decreases.

Market behemoth Samsung Electronics retreated 1.69 percent, and No. 2 chipmaker SK hynix plunged almost 4.5 percent.

Leading battery maker LG Energy Solution dropped 2.33 percent, and its smaller rival Samsung SDI went down almost 3 percent.

Steel giant Posco Holdings shot down 5.8 percent, and its battery component-making affiliate Posco Future M lost 4.52 percent.

Top chemical producer LG Chem went down 1.98 percent.

Auto shares also ended in negative terrain, with Hyundai Motor dropping 3.46 percent and its affiliate Kia losing almost 4 percent. Hyundai Mobis, Hyundai Motor's auto parts affiliate, sank almost 3.6 percent.

Bio stocks also went down, with Samsung Biologics losing 1.62 percent and Celltrion dropping 1.99 percent.

IT shares were bearish, with internet portal operator Naver falling 2.36 percent and Kakao, the operator of popular mobile messenger KakaoTalk, dropping 3.1 percent.

Kakao Bank plunged 5.23 percent on profit-taking despite a solid earnings report.

The Korean won ended at 1,298.5 won against the greenback, down 14.7 won from the previous session's close. (Yonhap)