MCDONALD'S Corp fell the most in more than four years after a franchisee survey indicated US same-store sales may have increased at their slowest pace since a turnaround in 2003.

Thirty-one franchisees who operate 195 US restaurants told consultant Richard Adams that December sales by outlets open at least 13 months advanced 1.8 percent.

According to Bloomberg News, Adams said competition from Burger King Holdings Inc and Wendy's International Inc hurt sales of McDonald's double cheeseburgers, a popular item on its dollar menu.

"Sales definitely slowed in December," Adams said. "For several years, McDonald's has benefited from the poor performance of Burger King and Wendy's, and now they're winning back some business."

Adams, a former McDonald's franchisee in San Diego, provides consulting services to about 300 of the company's franchisees. He prepared the sales survey for Mark Kalinowski, an analyst in New York who wouldn't elaborate beyond his report.

McDonald's fell US$3.85, or 6.6 percent, to US$54.32 in New York Stock Exchange composite trading on Friday, the biggest drop since May 2003. The stock has declined 7.8 percent this year after rising for five straight years.

McDonald's increased global same-store sales for 55 straight months through November, the longest string in 27 years. The introduction of meal-sized salads, grilled chicken sandwiches and a stronger coffee blend sparked the sales climb, as did the renovation of restaurants and lengthening of store hours to draw customers.

"If we see slowing sales, that's a signal for people to start getting out of the stock," Giri Cherukuri, who helps manage US$1.2 billion at Oakbrook Investments LLC, said. The Lisle, Illinois-based firm owns 200,000 McDonald's shares.

Through November, McDonald's same-store sales rose 4.9 percent in the US, slower than gains of 7.6 percent in Europe and 10.4 percent in the Asia/Pacific, Middle East and Africa region.