Bill Ackman, one of President Donald Trump’s staunchest defenders among major hedge-fund managers, published a post on X on Sunday urging a “90-day timeout” on some of the tariffs announced by the White House last week.

Otherwise, the U.S. was headed for a “self-induced, economic nuclear winter, and we should start hunkering down.”

Ackman’s comments came as U.S. stock futures opened sharply lower on Sunday evening, pointing to a third straight session of stock-market carnage on Monday.