Quarterly or Semiannual Financial Statements

Years of investing in global expansion and footwear is starting to pay off, Under Armour said Thursday after the Baltimore-based company reported a 34 percent jump in second-quarter sales that sent shares soaring.

The sports apparel maker's stock leapt nearly 15 percent Thursday to $69.55 per share.

Consumers are buying into the sports apparel maker's strategy of transforming itself into an international brand known for performance-based footwear as much as for its core clothing business, the company said. Better-than-expected sales prompted Under Armour to boost its sales forecast for the year to as much as $3 billion, a 29 percent jump from last year.

While the...