Wall Street's main indexes were on track for a lower open on Monday after President Donald Trump revealed plans to double tariffs on imported steel and aluminum, fueling more uncertainty around U.S. trade policies.

Wall Street has a new shorthand about President Donald Trump — and he’s not happy about it. Traders have reportedly come up with the acronym TACO, which stands for “Trump always chickens out,” to describe the tumultuous trade environment created by the president’s habit of threatening to impose tariffs on countries,