Icahn said in a statement on his website that he reduced his position in crane maker Manitowoc Co Inc for "legitimate investment reasons http://bit.ly/2Hbuo4z" and dismissed any speculation that his sale of shares was prompted by knowledge about Trump's plans.
Icahn in a regulatory filing on Feb. 22 said he sold roughly one third of his stake in Manitowoc, which uses steel to make its equipment, between Feb. 12 and Feb. 22, reducing his holding to 4.85 percent.
On March 1, Trump said he would impose 25 percent tariffs on steel imports and 10 percent on imported aluminum to make domestic production more attractive. The announcement weighed on certain stocks including Manitowoc, whose shares have fallen 4.4 percent since the announcement, through the market close on Tuesday.
"Any suggestion that we had prior knowledge of the Trump administration’s announcement of new tariffs on steel imports is categorically untrue," Icahn said in a three-line statement.
Manitowoc's shares had been falling steadily since Jan. 26 and are down 27.8 percent since the start of 2018.
Icahn first invested in Manitowoc in 2014 and said in a regulatory filing that the shares were undervalued.
Trump plans to formally announce the tariffs as soon as Thursday.
Icahn, who has been friendly with Trump for decades, served as a sounding board for Trump and was instrumental in vetting people for key positions before Trump was inaugurated in 2017.
Icahn ended his stint as an unpaid adviser in August. In November the 82-year old investor was subpoenaed by the U.S. Justice Department over his efforts to overhaul the U.S. biofuels program while he advised Trump, a regulatory filing shows.
Icahn's dual role as a presidential adviser and an investor with interests in multiple industries raised eyebrows with Democratic lawmakers and government watchdogs.
(Reporting by Svea Herbst-Bayliss in New York and Arunima Banerjee in Bengaluru; Editing by Leslie Adler)
By Svea Herbst-Bayliss and Arunima Banerjee