Boosting the role of financial markets in financing the European economy is the goal of the action plan to establish a capital markets union (CMU) among the 28 by 2019. The European Commission will present its plan before the end of 2015, most likely in late September.

The success of this keenly awaited initiative will probably depend on the level of ambition the executive sets on certain issues – highly sensitive in some European capitals – such as the approximation…