Frasers Group acquired a stake in embattled U.S. sportswear brand Under Armour, following a series of deals that are part of the British retailer's expansion strategy.

The group--founded by billionaire Mike Ashley--bought 16.6 million shares in Under Armour, representing 8.8% of the company, according to a filing.

The news comes as the U.S. brand is dealing with a challenging consumer environment, which hurt demand for its products. In August, the company lowered its revenue target for the year, citing weak demand trends, particularly in North America and the Asia-Pacific region.

Frasers, which usually buys stakes in other retail chains, recently achieved a near-majority ownership in German apparel group Hugo Boss, shortly after it acquired U.K. department store Harvey Nichols.