BALTIMORE, United States — Sportswear maker Under Armour Inc on Tuesday cut its full-year revenue forecast for North America, its biggest market, in the face of stiff competition from bigger rivals Nike Inc and Adidas AG, sending its share down 10 percent.

The company said it now expects a slight decline in North America revenue for fiscal 2019 compared with a prior forecast of flat revenue. Still, the company maintained its overall forecast.

Under Armour has been restructuring its operations to cut spending and inventories while reducing promotions as it struggles to keep its market share in the United States.

Sales in North America fell 3 percent to $816 million in the second quarter.

The company’s net loss narrowed to $17.3 million, or 4 cents per share, in the quarter ended June 30 from $95.5 million, or 21 cents per share, a year earlier.

Excluding certain items, Under Armour posted a loss of 3 cents per share, while analysts were expecting a loss of 5 cents.

Net revenue rose to $1.19 billion from $1.17 billion, roughly in line with analysts’ expectation.

Class A common shares of the Baltimore-based company have gained 55 percent so far this year.

By Aishwarya Venugopal; editor: Arun Koyyur.