LONDON - Euronext, Deutsche Boerse and 12 other European stock exchange groups on Thursday said they would jointly propose creating a combined feed of their share prices to investors, throwing down the gauntlet to rivals ahead of European Union legislation.

EU states and the European Parliament are due in coming months to finalise a draft law that would mandate exchanges to provide prices of stock transactions on their platforms to a low price "consolidated tape" (CT) for investors to spot the best deals.

Brussels wants to make its capital market deeper and more efficient by knitting a fragmented trading landscape. A tape has long been a feature of Wall Street. Banks and asset managers complain that the price of market data, a key money-spinner for bourses, is too expensive.

Once the draft law has been approved, the bloc's securities watchdog ESMA would oversee a selection process for a CT provider, and the exchanges, which also include Nasdaq, SIX Group in Spain, and bourses in Vienna, Prague and Warsaw, said they would submit a proposal.

"The participants are recognised specialists in supplying reliable and high-quality market data and are well positioned to deliver a CT quickly, efficiently, and to the highest operational standards," the exchanges said in a joint statement.

"The project will focus on providing a tape designed to provide a comprehensive, standardised and consistent source of market data and will seek to collaborate with regulators to develop the optimal solution for investors."

Bourses have called the CT proposal an "elaborate and complex experiment".

Past efforts to build a tape failed after exchanges refused to voluntarily provide data for a price that would make it viable.

The EU draft law proposes a tape showing prices which are "as close to real time as technically possible", but exchanges have lobbied for a CT with a delay of 15 minutes after a share transaction, a time gap which EU policymakers say would be of no use to investors.

(Reporting by Huw Jones; Editing by Shounak Dasgupta)