Investors focus on the Fed's policy decision and Chair Jerome Powell's news conference. Earnings from Meta and Microsoft are due after the closing bell.

Starbucks stocks slipped 0.2 per cent after reporting a weaker profit than analysts expected as it tries to turn around its operations.

Broadcom stock rallied 2% to hit a new high, while Palantir gained 0.4%, bouncing back from Monday's losses. Tesla skidded more than 1%, as it still tries to regain its 50-day moving average. And Uber stock steered 2.5% lower, threatening to breach its own 50-day line for the first time since late April.