The Trump administration has pressured Powell, whose term as Fed chair expires next year, to step down as chair of the central bank.

Wall Street will be listening closely to Federal Reserve Chair Jerome Powell's speech Friday at the Jackson Hole economic policy summit, where he could signal whether the central bank is ready to cut borrowing costs at its next meeting in September.

Wall Street is ticking lower in premarket trading as investors perused Walmart’s latest financial results ahead of Federal Reserve Chair Jerome Powell’s speech on Friday.