Seoul shares closed almost 1 percent lower Tuesday as investors became more cautious ahead of the US Federal Reserve's rate decision and earnings releases from global big techs this week. The local currency lost ground against the US dollar.

The benchmark Korea Composite Stock Price Index (Kospi) fell 27.34 points, or 0.99 percent, to close at 2,738.19.

Trade volume was slim at 376.4 million shares worth 9.9 trillion won ($7.1 billion), with losers far outnumbering winners 664 to 225.

Institutions and foreigners sold 355.2 billion won and 400 billion won worth of local stocks, respectively, offsetting individuals' stock buying valued at 729.2 billion won.

"Foreigners and institutions dumped local shares amid heightened risk-off mood ahead of the Fed's rate decision and earnings releases of tech giants due later this week," Lee Kyoung-min, an analyst at Daishin Securities, said.

This week, all eyes are on the Federal Open Market Committee meeting and earnings results of big tech firms, such as Apple, Amazon.com, Microsoft and Samsung Electronics.

Market behemoth Samsung Electronics fell 0.25 percent to 81,000 won, while No. 2 chipmaker SK hynix, a beneficiary of artificial intelligence (AI) chip giant Nvidia, slid 3.43 percent to 188,900 won on news that Apple used Google's AI chip to train its AI models.

Hanmi Semiconductor, a major chip equipment supplier, shot down 6.33 percent to 128,700 won.

Top carmaker Hyundai Motor plunged 2.15 percent to 250,000 won, and its smaller affiliate Kia shed 1.85 percent to 111,600 won. Its auto-parts making affiliate, Hyundai Mobis, also plunged 2.63 percent to 222,000 won.

Among the few gainers, leading battery maker LG Energy Solution climbed 1.06 percent to 333,000 won, and major shipping firm HMM advanced 1.86 percent to 17,550 won.

Korea Aerospace Industries, South Korea's sole aircraft manufacturer, soared 4.58 percent to 57,100 won on an earnings surprise.

The local currency ended at 1,385.90 won against the greenback, down 4.0 won from the previous session. (Yonhap)