Hyundai Motor Co. and affiliate Kia Corp. could face as much as $5 billion in additional costs this year under a new trade agreement between the US and South Korea that imposes a 15% import tariff on automobiles.

Shares in Hyundai and Kia, South Korea's leading automakers, sold off after the country struck a trade pact with the U.S. The country now faces a 15% [tariff on auto exports](

Shares of South Korean automakers Hyundai Motor (OTC: HYMTF) and Kia Corp declined on Thursday following U.S. President Donald Trumps announcement of a 15% tariff on imports from South Korea, including automobiles,