Shares of On Holding AG tumbled 6.29% in pre-market trading after the Swiss sportswear brand reported second-quarter net sales that fell short of Wall Street estimates, signaling challenges from a tougher consumer environment and higher costs related to U.S. tariffs.

The company posted net sales of 850.3 million Swiss francs, missing analysts' estimate of 878.16 million francs. Adjusted EBITDA also came in slightly below expectations at 168.1 million francs, compared to the consensus of 170.6 million francs. Sales growth in the core Americas market slowed to 13% in currency-adjusted terms, down from 17% in the prior quarter.

While the company raised its full-year gross profit margin outlook to at least 65% and emphasized its focus on profitability over volumes, the top-line miss and moderating growth in its biggest market appeared to weigh on investor sentiment. The company is deliberately managing wholesale sell-in to protect full-price integrity in a promotional marketplace.