Markets had dismissed tariff risks under the assumption that Trump would follow an earlier pattern and back off, in what became known as the so-called TACO trade. That allowed stocks to reach new record-high territory recently, marking a stunning rebound from the collapse triggered by his “Liberation Day” reciprocal tariffs in April.

The U.S. dollar rose on Friday on more signs of upheaval in the global trade landscape, as U.S. President Donald Trump announced more tariffs and said he planned to impose blanket levies of 15% or 20...