Wall Street's main indexes opened lower on Tuesday ahead of the Federal Reserve's policy meeting, with investors awaiting grocery delivery app Instacart's Nasdaq debut to assess a potential recovery in the IPO market.

The Dow Jones Industrial Average fell 52.46 points, or 0.15 percent, at the open to 34,571.84. The S&P 500 opened lower by 8.12 points, or 0.18 percent, at 4,445.41, while the Nasdaq Composite dropped 60.79 points, or 0.44 percent, to 13,649.44 at the opening bell.