Bill Ackman, a hedge fund manager and Trump supporter, expressed concern over President Donald Trump‘s tariff plan.
In a post on X, Ackman doubted the strategy the Trump administration used to calculate the tariff rates for each country, saying the global economy was being “taken down by bad math.”
“The formula used by the administration to calculate tariffs made other nations’ tariffs appear four times larger than they actually are,” Ackman said, linking to an American Enterprise Institute article that said the math doesn’t make “economic sense.”
“The President’s advisors need to acknowledge their error before April 9th and make a course correction before the President makes a big mistake based on bad math,” Ackman said.
The post came less than 24 hours after Ackman called for Trump to put a 90-day pause on implementing his tariff plan. Ackman said the United States could “severely damage” its trading reputation if it moved forward with enacting reciprocal tariffs.
“The president is losing the confidence of business leaders around the globe,” Ackman said. “The consequences for our country and the millions of our citizens who have supported the president — in particular low-income consumers who are already under a huge amount of economic stress — are going to be severely negative. This is not what we voted for.”
Ackman endorsed Trump in July, saying, “I assure you that I have made this decision carefully, rationally, and by relying on as much empirical data as possible.”
While Ackman raised concerns of “an economic nuclear war,” he walked back his criticism of Commerce Secretary Howard Lutnick. Ackman previously accused Lutnick of not being concerned about the harsh drop in the stock market, alleging the commerce secretary was only invested in “long bonds.”
LIST: THE EXECUTIVE ORDERS, ACTIONS, AND PROCLAMATIONS TRUMP HAS MADE AS PRESIDENT
“It was unfair of me to lash out at @howardlutnick,” Ackman said Monday morning. “I don’t think he is pursuing his self interest. I am sure he is doing the best he can for the country while representing the President as Commerce Secretary.”
Ackman said he’d love to be “proven wrong” about his predictions that the tariffs would escalate into a trade war and erode foreign powers’ confidence in the U.S.