Bill Ackman, a Trump billionaire, is calling for a 90-day pause on tariffs and warns of an "economic nuclear winter

Trump ally Bill Ackman has warned that the world is on the brink of an 'economic nuclear winter' as he begged the president to hit pause on his reciprocal tariffs. 

 The president's 10 percent 'baseline' tariff began Saturday, hitting all US imports except goods from Mexico and Canada.  Come April 9, higher levies on goods from 57 larger trading partners - including the European Union. 

 The tariffs caused stock markets across the world to plummet and on Sunday night, 'Black Monday' started trending on X - a reference to the global and severe stock market crash of 1987.

 Now, Trump's seismic moves have caused some of America's brightest business minds to lose their confidence in him, including Pershing Square Capital Management's CEO, Ackman.   

 The S&P 500, Nasdaq, and Dow, the three primary indices of the U.S. stock market, are on track to open Monday morning down by as much as 6%, according to experts. Japan's Nikkei sank by as much as 8% over Friday in early morning Asia trading, while Australia's market was down 6%, South Korea's was down 5%, Taiwan was down almost 10%, Singapore was down 8.5%, Hong Kong was down 10%, and China was down almost 5%. Over the past six months, the S&P/ASX 200 was also down nearly 13 percent.

 It followed the worst two-day wipeout in US stock market history on Thursday and Friday — with $6.6 trillion wiped off the value companies, which analysts now say may just be the beginning.

 Yet Trump has largely shrugged off the economic downfall, telling reporters on Sunday that even though world leaders have been reaching out to him to negotiate trade deals he has brushed off their requests and defiantly continued on with his plans.   

 Ackman, however, saw things differently - warning that Trump's current trajectory could devastate businesses around the world.