If at first you don’t succeed

Nasdaq has certainly picked its moment to pounce on the London Stock Exchange. As recently as the beginning of last week, shares in the UK group were trading over £13, which many believed was too rich for Nasdaq to return for a second bite at the group it first tried to buy eight months ago. But the shares fell on news that seven leading investment banks are to set up a rival European exchange, which raised fears that competition would drive down LSE’s fat margins. That may make nervy investors...