Carl Icahn, a former special adviser to President Donald Trump, is facing allegations of possible insider trading after a federal filing revealed the billionaire investor started selling off millions of dollars in stock for a company that significantly depends on steel just a few days before the Trump administration started publicly considering a steel tariff, which the president officially announced Thursday.

As Common Dreams reported Thursday, Trump flouted warnings of a trade war from several members of his cabinet and announced that he will impose a 25 percent tariff on steel imports and 10 percent on aluminum—a decision that may have been helped along by the industry's six-figure ad buy that appeared on major cable networks. That move followed a Feb. 16 report from Trump's Commerce Secretary Wilbur Ross, which called for a 24 percent steel tariff.

Although Ross's public report served as a signal to investors and traders that the administration was at least considering a tariff, as Judd Legum at ThinkProgress first reported on Friday, a Feb. 21 SEC filing shows that four days before the report was published, Icahn started ditching what would amount to $31.3 million in shares of Manitowoc, "a leading global manufacturer of cranes and lifting solutions."

1. Wow, Trump confidant Carl Icahn is such a LUCKY GUY. Right before Trump announces a steel tariff that tanks manufacturing stocks, he dumped 1 MILLION SHARES of the one of the companies that was hardest hit. Such a fortunate coincidence.https://t.co/HL4wYHivLY — Judd Legum (@JuddLegum) March 2, 2018

"Icahn was required to make the disclosure because of the large volume of his sale. The filing reveals that he began systematically selling the stock on February 12, when he was able to sell the stock for $32 to $34," Legum noted. Meanwhile, on Thursday, "Trump's announcement rattled the markets, with steel-dependent stocks hardest hit. Manitowoc stock plunged, losing about 6 percent of its value."

After the report was published, Legum added updates from regulatory filings. "The new information makes the sale look even more suspect," he concluded, outlining the additions in a series of tweets:

3. He was required to disclose the sale on Feb 23rd because his ownership stake dropped below 5%. It still showed him with a substantial holding. But now that he is below 5% he doesn't have to disclose his sales anymore. He could have kept selling https://t.co/NwzdUDYh4o — Judd Legum (@JuddLegum) March 2, 2018

The ThinkProgress report spurred a flurry of speculation about insider trading:

Hmmm, is this a coincidence or did Trump confidant Carl Icahn have insider information? https://t.co/5sP2MUbg59 — Ted Lieu (@tedlieu) March 2, 2018 ICAHN…totally believe it was insider trading https://t.co/auqFW3D2lb — Man Bartlett (@man) March 2, 2018

Some pointed to past allegations levied against Icahn, as well as his resignation from his position in the Trump administration.

Recall that a year ago, Bloomberg reported that, while working as a Trump adviser, Carl Icahn lobbied for a rule change in which he directly benefited. https://t.co/QgyIWWD0T8 https://t.co/jaKAs70Hrp — Matt Ortega (@MattOrtega) March 2, 2018 Last year, Carl Icahn had to resign as a WH “special adviser” when he allegedly used his close ties to Trump to protect his investments. Icahn might be at it again https://t.co/pykze0OH4W — Chris Lu (@ChrisLu44) March 2, 2018

Icahn resigned from his position as a special adviser to the president just before the publication of a New Yorker story that outlined conflicts of interest with his business investments and the appointment. Critics described it "as a kind of corporate raid on Washington," including one who quipped, "It's the cheapest takeover Carl's ever done."