LONDON, Nov 21 (Reuters) - The European Union has reached an outline deal on capping "dark" or off-exchange trading in shares to shine a light on opaque corners of the market, sources familiar with the negotiations said on Thursday.
The bloc is finalising an update of its securities trading rules, known as Markets in Financial Instruments Directive or MiFID, to reflect lessons from the 2007-09 financial crisis and rapid advances in trading technology.
Trading in a stock anonymously will be capped at 8 percent of the total amount traded of that stock in the EU.
So-called dark pool trading in a stock on an individual platform would be restricted to no more than 4 percent of the total EU market for that stock.
The sources said that the EU's executive European Commission will conduct further work on how the caps would work in practice, such as what happens when a cap is breached.
The European Securities and Markets Authority would collate data on share trading gathered by national authorities, the sources added.