Stock-market investors know that Federal Reserve decision days — and the day after — can be volatile. But there’s a twist when it comes to Wednesday’s policy decision. U.S. financial markets will be closed Thursday in observance of the Juneteenth holiday.

Financial markets may be in for a "knee-jerk" selloff if the U.S. military attacks Iran, with economists warning that a dramatic rise in oil prices could damage a global economy already strained by President Donald Trump's tariffs.