McDonald's Corp. (MCD), the world's largest fast-food chain, forecast third-quarter earnings above Wall Street's expectations Thursday after posting strong increases in same-store sales for September. Its stock jumped to a new six-year high.

The company said systemwide same-store sales, or those from restaurants open at least 13 months, climbed 9.8 percent in September and 8.4 percent in the third quarter, driven by strong growth in Europe.

Same-store or comparable sales are a widely used gauge of industry performance. Excluding non-McDonald's brands, same-store sales rose 7.7 percent in September and 5.8 percent in the third quarter.

The company said McDonald's U.S. same-store sales grew 7.1 percent in September and 4.1 percent in the third quarter, driven by the new Snack Wrap offering. European same-store sales climbed 9 percent in September and 7.6 percent during the quarter, with growth especially strong in Germany, France and Britain.

In the Asia/Pacific, Middle East and Africa regions, same-store sales rose 6.6 percent in September and 6.1 percent for the quarter, helped mainly by results in Japan.

Looking ahead, McDonald's said it forecasts third-quarter earnings of 68 cents per share, up sharply from analysts' consensus estimate of 63 cents per share, according to a poll by Thomson Financial.

Shares rose $1.04, or 2.5 percent, to $42.29 in morning trading on the New York Stock Exchange — their highest level since Jan. 20, 2000.