Tyson, McDonald's down on heels of mad cow disease

NEW YORK - Investors are getting their first chance to react to the apparent discovery of mad cow disease in the U-S. Stock prices are lower for a number of companies with potential business exposure to the scare.

Among them, McDonald's shares are down six percent in early trading. Processor Tyson Foods, which also handles chicken and pork, is seeing its stock lose nearly seven percent of its value.

Other stocks hit include Wendy's, Lone Star Steakhouse and Rare Hospitality International.

Federal officials are insisting the food supply is safe. But large importers such as Japan, South Korea and Taiwan, have halted U.S. beef import.

Japan is the largest overseas market for U.S. beef.