Swiss shoemaker On Holding AG said the strength of the franc will dampen its ability to fully capitalize on explosive growth in its US sneaker sales later this year.

The Roger Federer-backed company nudged its full-year sales guidance higher to at least CHF1.76 billion ($2 billion) on 15 August. Analysts are expecting CHF1.78 billion. The stock, which trades in New York, fell 8.9% in trading before US exchanges opened.

The Zurich-based company would have raised the forecast to meet the consensus were it not for the weakening of the US dollar since May, according to co-CEO Martin Hoffmann.

“We will have a major currency impact,” he said in an interview. “We really continue to have the strong growth aspiration in the guidance, but it’s a bit overshadowed by the FX.”

The Swiss franc has gained 7.9% against the dollar in the past 12 months. Economists expect the Swiss National Bank to raise interest rates for a final time in September, which has given support to the currency. The franc is also trading near a record against the euro.

Nonetheless, On is still enjoying rapid growth in the US, thanks to an expanding line-up of footwear and increasing availability at retailers like Dick’s Sporting Goods Inc. That’s helping On take market share from bigger rivals like Adidas AG, Nike Inc. and Puma SE. 

Second-quarter sales of CHF444 million exceeded the CHF418 million average analyst estimate. 

Shares in On have doubled this year, far outperforming Nike and Puma. That’s putting pressure on the company to keep reporting strong growth to justify its share performance. 

The Swiss brand said on 15 August that second-quarter sales jumped 60% in the Americas to reach CHF297 million, while revenue in Europe increased 29% to CHF114 million.

On is seeing lots of momentum in the US with retailers like Dick’s and Foot Locker Inc, according to Hoffmann.

“We are only in a bit over 50 Dick’s stores out of the 800 that they have,” he said. “So there’s a huge untapped market potential.”