CESR said the introduction of MiFID in November 2007 significantly changed Europe's secondary market landscape, most notably through the introduction of Multilateral Trading Facilities (MTFs).
The report found that the increased competition between trading venues caused by MTFs has created "downward pressure" on direct execution costs. However, this has been largely offset by an increase in spending on technology in order to trade in a more fragmented environment and a general widening of bid-offer spreads because of market volatility.
Market participants also have concerns over pre-trade transparency, ranging from interpretation issues to "potentially undesirable" impacts on innovation and the creation of an unlevel playing field between trading venues.
In the review, chair of the CESR MiFID expert group Jean-Paul Servais said: "Despite the difficult market conditions of the past 19 months, MiFID has created a new dynamism and increased competition into equity secondary markets."
Although it is still early in MiFID's implementation, he added it was possible to identify areas "where further work may be required".