Shares of Watches of Switzerland Group Plc fell as much as 25% on concerns the biggest retailer of Rolex watches in the UK could suffer falling sales after the Swiss brand bought retailer Bucherer AG.

Rolex unveiled a surprise move to buy Bucherer late Thursday, marking its first major move into retail.

In a statement, Watches of Switzerland said it had received assurances from Rolex management that there “will be no change in product allocation or distribution as a consequence of the acquisition.”

However, that didn’t stop Watches of Switzerland shares from falling as much as 25.7%. They were down 24% as of 8:15 am London time.

Analysts speculated that the deal could be a blow for retailers of Rolex watches.