Dec 5 (Reuters) - Wall Street's main indexes opened lower on Monday as investors maintained a cautious stance ahead of data, including a report on the U.S. services sector, to gauge the Federal Reserve's next move at its rate-setting meeting later this month.

The Dow Jones Industrial Average fell 94.1 points, or 0.27%, at the open to 34335.73. The S&P 500 dipped 19.7 points, or 0.48%, at the open to 4052.02, while the Nasdaq Composite dropped 80.5 points, or 0.70%, to 11380.991 at the opening bell. (Reporting by Ankika Biswas in Bengaluru; Editing by Sherry Jacob-Phillips)