Stock exchanges are warning they could be forced to pull Swiss shares from their trading venues within weeks because of Switzerland’s political standoff with the European Union — with the London Stock Exchange the latest to sound the alarm.

The LSE said late afternoon on June 25 that it is preparing to halt trading in 254 shares issued by Swiss companies on July 1, the first trading day after Switzerland’s current agreement with the EU expires. The trades take place on the LSE’s XLOM trading venue.