Billionaire investor Carl Icahn is denying that he knew about President Trump's steel tariff plan before it was formally disclosed.

Why it matters: Icahn sold at least part of his stake in The Manitowoc Co., which relies heavily on steel, ahead of Trump's announcement last Thursday. The stock has since fallen more than 5%, but Icahn — who once served as an unpaid economic advisor to Trump — had declined comment until today.

Icahn's statement:

" Any suggestion that we had prior knowledge of the Trump administration’s announcement of new tariffs on steel imports is categorically untrue . We reduced our position in Manitowoc for legitimate investment reasons having nothing to do with that announcement.”

What we still don't know: If Icahn has sold more Manitowoc shares since his initial disclosure, and what those "legitimate investment reasons" were.