NEW YORK (AP) — An analyst lowered his rating for McDonald's on Wednesday, saying that a key revenue metric may drop slightly over the next few months.

Bryan Elliott of Raymond James reduced McDonald's Corp. to "Market Perform" from "Outperform." In a client note, the analyst said that over the next few months the world's biggest hamburger chain may see a slight decline in revenue at U.S. locations open at least 13 months as it contends with more difficult comparisons and a payroll tax increase on all U.S. wage earners.

After years of outperforming its rivals, McDonald's has seen sales growth slow as the company faces intensifying competition and an uncertain global economy. Its global revenue at restaurants open at least 13 months fell 1.8 percent in October. The last time it had dropped was in March 2003. But the figure rebounded in November, rising 2.4 percent.

McDonald's has responded to slowing sales growth by renovating some stores and expanding its value menu and adding other food items to its menu.

Elliott said that he is growing more cautious on global economic conditions as demand softens in many markets. The analyst said that there are no visible catalysts to help boost broad consumer spending.

The stock fell 37 cents to $90.57 in premarket trading. They have traded in a 52-week range of $83.31 to $102.22.