A political dispute between the European Union and Switzerland threatens to disrupt their economic relations. On June 24, the Swiss government said it was ready to ban EU stock exchanges from trading Swiss shares if the European Commission follows through on a threat not to extend the stock market equivalence rights that the European Union grants to Switzerland when they expire June 30. If these tit-for-tat measures are enforced, investors in the European Union and Switzerland could find it harder to access each other's stock exchanges....