Shares of South Korea’s Hyundai Motor Group affiliates saw their stocks slump Monday after an announcement that the carmaker is not in talks with US tech giant Apple for a self-driving vehicle project.

Shares of Hyundai Motor crumbled 6.21 percent to 234,000 won ($208.94), with its smaller affiliate Kia plunging 14.98 percent to 86,300 won, at the closing bell. The firms at one point plummeted as much as 8.42 percent and 15.27 percent, respectively, in the early morning trade.

Other key affiliates of Hyundai Motor Group also retreated. Auto parts makers Hyundai Mobis and Hyundai Wia collapsed 8.65 percent and 11.9 percent, while the vehicle delivery arm Hyundai Glovis crashed 9.5 percent.

Amid Hyundai shares plunging, the combined market capitalization of the group’s affiliates sharply dropped 13.5 trillion won in a day, to nearly 125.4 trillion won.

The stocks’ sudden losses resulted from Hyundai and Kia’s announcements through separate regulatory filings Monday that they aere “not in talks with Apple over developing an autonomous vehicle.” The two firms are still reviewing prospects of cooperating with “multiple companies overseas” regarding a self-driving electric vehicle production, the filings showed.

Along with the top automakers’ tumbling shares, the local indexes traded bearishly. The main bourse Kospi dipped below the 3,100-point mark, ending the Monday’s trading by 0.94 percent lower to 3,091.24 points. Foreigners’ heavy selloff worth a net 356.2 billion won weighed down the market.

In the wake of foreign and institutional investors’ net sales, the tech-heavy Kosdaq also shed 0.69 percent to 960.78 points. Both foreigners and institutions extended selloffs for three consecutive sessions.

By Jie Ye-eun (yeeun@heraldcorp.com)