Cohn, a free-trade advocate who opposed implementing tariffs, resigned Tuesday night, five days after Trump announced plans for tariffs on steel and aluminum imports. The resignation signaled an increased likelihood that Trump would implement the tariffs.
Since Trump's announcement, shares of metal users have been mostly under pressure. In that period, GM and Boeing are down more than 3.5 percent, while United Technologies is down 2.3 percent. Ford, however, is up 0.2 percent.
News of Cohn's resignation sent U.S. stock indexes falling amid growing worries of a trade war. The Dow Jones industrial average declined more than 130 points.
Cohn was seen by Wall Street as a voice of reason in a White House that is seemingly in constant turmoil. His presence in the White House was also well-liked by investors given his track record on Wall Street. Prior to working in the Trump administration, Cohn was president and COO at Goldman Sachs.