Banks, trading firms and stock exchanges are still in the dark on a number of tenets making up the EU’s revised trading rulebook, following disagreement and protest at a crunch meeting of policymakers.

A group of officials from the European Commission, finance ministries, central banks and national regulators - known collectively as the Expert Group of the European Securities Committee - met in Brussels on Tuesday to discuss a revision of the Market in Financial Instruments Directive, or Mifid II, which comes into force in January 2017.