Trump supporter and billionaire Bill Ackman warns of 'economic nuclear winter,' urges 90-day halt on tariffs

The billionaire investor says Trump's sweeping tariffs are shaking global markets and eroding business confidence.

Billionaire investor and vocal Trump supporter Bill Ackman has issued a stark warning, calling the president's tariff strategy a potential trigger for an "economic nuclear winter."

Ackman, CEO of Pershing Square Capital Management, took to X on Sunday to urge President Trump to "call a 90-day timeout" to allow room for negotiations on unfair trade practices.

“The president has an opportunity to call a 90-day timeout, negotiate and resolve unfair asymmetric tariff deals and induce trillions of dollars of new investment in our country,” Ackman wrote.

But if the tariffs continue, Ackman warned, the result could be catastrophic. “If, on the other hand… we launch economic nuclear war on every country in the world, business investment will grind to a halt, consumers will close their wallets and pocketbooks, and we will severely damage our reputation with the rest of the world.”

Ackman’s comments come after Trump's 10% blanket tariff on most imports took effect Saturday, with an additional wave targeting 57 trading partners—including the EU—set to activate on April 9.

The billionaire investor did not hold back, stating, “By placing massive and disproportionate tariffs on our friends and our enemies alike… we are in the process of destroying confidence in our country as a trading partner, as a place to do business and as a market to invest capital.”

Markets have already started to react. On Monday morning, Japan’s Nikkei plunged by as much as 20%, while indices in Australia, South Korea, Taiwan, and China all saw significant losses.

Closer to home, the S&P 500 and Nasdaq are expected to open down by as much as 6%. “This is not what we voted for,” Ackman stated bluntly.

While Trump has dismissed concerns, saying “they’re dying to make a deal,” and insisting any trade agreement must eliminate deficits, critics warn that the current trajectory could mirror the infamous Black Monday crash of 1987.

“I have a lot of respect for our president and what he has accomplished so far,” Ackman noted, “but I don’t think he is infallible.” He ended his series of posts with a clear plea: “The right answer… is a 90-day pause.”