European regulators want to toughen up new rules on the fees stock exchanges can charge for data, a topic which could form an important component of the European Union's planned capital markets union.

A revision of the EU's flagship trading rulebook, called the Markets in Financial Instruments Directive, aims to tackle the perceived high costs of market data in Europe as well as bring increased access to data feeds. A study last year by consultancy Oxera, showed that the fee for a US consolidated tape of data is €58 a month compared with the €430 a month that it costs Bloomberg to combine all the direct feeds from European exchanges.