Materials, energy stocks weigh on indexes

Wall Street looked set to snap a two-day rally on Monday as retreating crude oil prices weighed on materials and energy stocks. Investors, already rattled by the volatile start to the year and a steep fall in oil prices, are awaiting U.S. GDP data on Friday for a reading on the health of the economy. All eyes will be on the U.S. Federal Reserve's next move on interest rates when the Federal Open Market Committee meets on Jan. 26-27.