US stock index futures dipped on Wednesday as investors waited for the Federal Reserve’s decision on interest rates in what has been a rocky week for global markets.

The central bank is expected to lower interest rates by a quarter percentage point for the second time in three months, but a deep divide among policymakers has seen traders abandon all bets on a third reduction this year.

The Fed’s policy statement is due at 2 p.m. followed by Chair Jerome Powell’s address a half-hour later.

Central banks around the world have been taking steps to cushion the impact of a prolonged US-China trade war and other geopolitical risks. Last week, the European Central Bank cut interest rates further and said it would buy back bonds indefinitely.

Expectations of lower rates have spurred a Wall Street rally this year, with the benchmark S&P 500 now less than 1 percent below its all-time high.

Markets had come under pressure earlier this week after attacks on Saudi Arabia’s oil facilities caused a spike in oil prices and fueled geopolitical tensions.