Former men's tennis world number one Swiss Roger Federer is seeing the value of his holdings in an apparel maker decline.

Apparel maker On Holding saw its shares slump in premarket trade as the Zurich-headquartered, U.S.-listed company guided to weaker-than-expected sales for the year.

Saying it is taking a "disciplined" approach, On said it would protect "full-price integrity in a promotional marketplace" ahead of what it termed "breakthrough innovations" heading into 2027.

That means it's guiding for full-year sales between 3.47 billion francs ($4.3 billion) to 3.56 billion francs, compared to the Visible Alpha-compiled analyst estimate of 3.57 billion francs.

On said it swung to a second-quarter adjusted earnings per share of 0.35 francs a share, beating expectations of 0.34 francs, as sales increased by 13.5% to 850.3 million francs. Analysts had expected revenue of 884 million francs, according to Visible Alpha.

On Holding shares $(ONON)$ slumped 14% in premarket trade.

For Roger Federer, who is reported to own about 3% of the company, that move translates into a roughly $50 million decline in the value of his holdings. Federer has helped create the company's "The Roger" line of sneakers.

Forbes last year said Federer was worth $1.1 billion.

-Steve Goldstein