U.S. stocks were set to open in green territory on Tuesday ahead of the Federal Reserve two-day policy meeting. The Fed is expected to increase its interest rates for the third time this year.
The S&P 500 inched up 0.1%, to 2662.
The Dow Jones Industrial Average gained 0.3%, to 24445.
The Nasdaq Composite slipped 6 points to 6870. Energy sector advanced and shares of Boeing scaled a record peak.