A “pivotal question” is whether the slowdown in the athleisure company’s U.S. business is temporary “or a sign of something more fundamental,” UBS says.

Lululemon Athletica's shares fell 20% in premarket trading on Friday, as the maker of high-end leggings warned that tariff-related costs and uneven demand in key markets of North America and China will dent its profits this year.

The apparel maker’s stock fell nearly 20% after the company lowered its earnings forecast, citing the trade war and a pullback in consumer spending.