At a glance, the past year has been a sunny one for commerce. In the U.S., stock and house prices are riding high, and consumer sentiment is as good as it has been in decades. The latest reading on the economy shows it is growing nicely.

But business leaders have faced some awkward surprises. Tariffs have complicated supply chains. Banks preparing for an earnings boost on rising interest rates now find that rates are expected to fall again. Car makers and semiconductor firms have hit a demand slump. Big tech outfits are being...