Fast-food company Yum Brands Inc. (YUM) Thursday said sales at U.S. restaurants open at least a year rose 5 percent in the four weeks ended Sept. 4, helped by a rebound at its KFC fried chicken chain.

Louisville, Ky.-based Yum also backed Wall Street analysts' average earnings estimate for the third quarter of 60 cents per share, saying that sales strength should offset higher U.S. commodity costs.

The company's stock rose $1.22, or more than 3 percent, to $40.55 following the announcement, which exceeded several Wall Street analysts' expectations.

Yum said same-store sales, a key measure of retail strength, climbed 4 percent at KFC (search), which the company is trying to turn around. It was the chain's second straight month of same-store sales gains after eight months of negative or flat results.

The results were ahead of Prudential analyst Larry Miller's forecast, which predicted flat same-store sales at KFC and an overall rise of 2.7 percent.

The strong performance was also boosted by a 7-percent same-store sales rise at Taco Bell (search) and a gain of 3 percent at Pizza Hut (search).

International sales rose 17 percent in the period, helped by the weaker dollar. Excluding currency conversion, international sales rose 11 percent, the company said.

For Yum's third quarter, U.S. same-store sales rose 4 percent.

Yum also stood by its forecast for full-year earnings of at least $2.33 a share, or $2.36 a share excluding one-time items. Analysts on average forecast $2.34 a share, according to Reuters Estimates.