Shares of steel and aluminum producers tumbled across the board post-market Wednesday following President Trump's tariff announcement, even as The White House said steel and aluminum imports would be exempt from reciprocal tariffs.

European Union member states voted Wednesday to approve retaliatory tariffs on $23 billion in goods in response to President Trump’s 25% tariffs on imported steel and aluminum, as the largest U.S. trading partner described them as “unjustified and damaging.

Steel and aluminum are essential for high-rise construction, and are often cheaper to produce in countries like China, Mexico or Canada, one expert said.