"Alternatively, we are heading for a self-induced, economic nuclear winter, and we should start hunkering down. May cooler heads prevail," the billionaire wrote on X. Ackman said the impact of tariffs will be particularly harsh for low-income Americans.

Trump reacted for the first time on Thursday to the fallout from his tariff announcement, which included markets nosediving and foreign leaders threatening retaliation.

Mega-cap tech stocks led the rout, with Apple posting its worst two-day drop since March 2020. Financial stocks also suffered steep losses.

The tariffs have raised costs for companies, which have had to cut workers and raise prices. Uncertainty has deterred investments. Meanwhile, China’s trade surplus has grown.