Howard Lutnick, chairman and CEO of investment firms Cantor Fitzgerald and BGC Group, told the U.S. Senate Committee on Commerce, Science and Transportation that he would divest “all of my interests, my business interests, all of my assets, everything.”

WASHINGTON—Howard Lutnick’s journey from Wall Street veteran to one of President Trump’s most hawkish trade advisers began with a speech at an October campaign rally at Madison Square Garden. Lutnick extolled the virtues of tariffs and argued that the duties could at least in part replace the U.