The No. 1 hamburger chain's shares fell 1.6 percent to $55.33 in midday trading on the New York Stock Exchange and dragged down the stocks of rivals Yum Brands Inc
Closely watched same-store sales rose 3.5 percent in Europe, helped by Britain and France, and were up 1.7 percent in the United States, where intense fast-food price competition weighed on results. Comparable sales slipped 0.5 percent in the company's Asia Pacific, Middle East and Africa (APMEA) segment, McDonald's said on Wednesday.
Analysts had expected U.S. same-store sales to rise 2.8 percent. On a global basis, some estimates called for a same-store sales increase of as much as 3 percent.
U.S. same-store sales are mired in the low single-digit range, Jefferies & Co analyst Jeff Farmer said in a client note.
Farmer expects McDonald's U.S. same-store sales to remain below 4 percent for the balance of the year, making a sustained move to $60 very difficult for the shares.
The world's largest hamburger chain said its U.S. sales were supported by the new premium Angus Third Pounder burger and new McCafe coffee drinks.
McDonald's and some other fast-food restaurants have benefited as the global economic downturn has led diners to seek lower-priced fare, but long-term economic doldrums and a 9.7 percent U.S. unemployment rate have taken a bite out of profitable breakfast and beverage sales.
McDonald's said systemwide sales rose 1.1 percent in August, but were up 4.1 percent excluding the impact of currency fluctuations.
Stifel Nicolaus analyst Steve West said he expects foreign exchange to have a less negative impact going forward.
Due to diners' continued cautious spending, McDonald's has turned its advertising focus to its core and value menus and away from higher-priced food items -- with the exception of the new Angus burger, which is being introduced across the United States.
Shares in Yum, which owns the KFC, Taco Bell and Pizza Hut brands, were down 1.9 percent at $33.54, while Burger King's stock was off less than 1 percent at $18.00.
(Additional reporting by Martinne Geller; editing by Gerald E. McCormick and Maureen Bavdek)