South Korea's benchmark stock index slumped below the 3,100-point mark Monday despite spreading optimism for an economic rebound, largely on losses by Hyundai Motor and its affiliate Kia Corp. as the two automakers said they are not in talks with Apple Inc. over an electric vehicle project. The Korean won rose against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 29.39 points, or 0.94 percent, to close at 3,091.24 points.

Trading volume was high at about 1.3 billion shares worth some 19.1 trillion won ($17.1 billion), with losers outnumbering gainers 458 to 390.

Foreigners sold a net 359 billion won, while retail investors purchased a net 86 billion won. Institutions bought a net 280 billion won.

The stock market slumped as Hyundai and Kia said they are considering forming a partnership with foreign companies for self-driving electric vehicles but are not in talks with Apple.

Amid the automakers' struggle, battery and chemical heavyweights also fared weak.

"Had it not been for the Hyundai (and Apple) related issue, the KOSPI could have seen gains," said Shinhan Financial Investment analyst Choi Yoo-joon.

"Expectations for an economic recovery also stoked speculation about a rate hike, together pulling up the bank- and financial-related shares," he said.

Top automaker Hyundai Motor tumbled 6.21 percent to 234,000 won. Kia plunged 14.98 percent to 86,300 won, and auto parts maker Hyundai Mobis plummeted 8.65 percent to 322,000 won.

Top cap Samsung Electronics lost 0.6 percent to 83,000 won, and No. 2 chipmaker SK hynix shed 1.96 percent to 125,000 won.

Leading chemical firm LG Chem retreated 3.7 percent to 990,000 won, while rechargeable battery maker Samsung SDI moved down 0.65 percent to 770,000 won.

Giant pharmaceutical firm Samsung Biologics went down 0.99 percent to 804,000 won, and Celltrion fell 1.61 percent to 336,000 won.

Internet portal operator Naver declined 1.38 percent to 357,500 won, but its rival Kakao gained 0.44 percent to 457,000 won.

The local currency closed at 1,119.6 won against the US dollar, up 4.1 won from the previous session's close. 

Bond prices, which move inversely to yields, closed lower. The yield on three-year Treasurys rose 1.9 basis points to 1.001 percent, and the return on the benchmark five-year government bond added 1.6 basis points to 1.327 percent. (Yonhap)