Wendy's ( WEN) said Friday that its fourth-quarter same-store sales climbed 3.1% at company-owned restaurants, bolstered by particularly strong results in December.

The burger chain's same-store sales jumped 6.1% in December, its strongest month in two and a half years.

The results show a sharp turnaround from 2005, when Wendy's posted its first annual same-store sales decline in 18 years. The company has since installed a new CEO, enacted a revitalization plan and set a promise of returning $1 billion to shareholders.

For all of 2006, Wendy's same-stores sales rose 0.8% at company-owned stores, and 0.6% at franchises.

"Our strong promotional calendar, menu management, product innovation and improved marketing have been the driving forces behind the positive sales momentum we have generated over the past three quarters," CEO Kerrii Anderson said. "We expect to see similar quarterly sales results in the coming year and anticipate a strong start in 2007."

In the first quarter, the company plans to promote new "deluxe value meals" at a suggested price of $2.99, lower than its regular meals. The company also plans limited-edition menu items such as a cranberry pecan chicken salad and a bacon mushroom melt cheeseburger.

Shares of Wendy's recently were up 20 cents, or 0.6%, to $33.86.