Though the USDA announced in December that a cow in Washington state had tested positive for bovine spongiform encephalopathy (BSE, known as mad cow disease), consumer confidence in U.S. beef supplies has not wavered as some investors expected. With the confirmation that the infected cow was imported from Canada, investors confidence in McDonald’s, Wendy’s, and Jack in the Box has returned.

McDonald’s (MCD) stock dropped $1.32 after the announcement from $25.28 at closing on December 23 to $23.96 at closing on December 24—its lowest point in two months. It closed yesterday at $25.50, its highest point since the BSE announcement.

Wendy’s (WEN) stock fell $1.87 with a closing price of $39.66 on December 23 and a closing price of $37.79 on December 24—its lowest price in a month. It rallied to close at $40.15 on January 6, but closed at $38.66 Thursday.

Jack in the Box’s (JBX) stock closed down $1.24 after the mad cow disease announcement, dropping from $22.00 on December 23 to $20.76 on December 24. Jack in the Box closed Thursday at $23.15, its highest price since July.