Nasdaq OMX (NDAQ) announced Tuesday plans to launch a European "dark pool," granting the exchange company a berth in the battle for massive stock trades in Europe.

Dark pools are private markets in which buyers and sellers connect and trade large blocks of equities anonymously.

Aimed at high-frequency trading shops, Nasdaq OMX Europe's planned dark pool platform, Neuro Dark, is set to launch April 27, trading about 800 European blue-chip stocks, according to the company.

The announcement follows a similar platform from rival NYSE Euronext (NYX) called SmartPool that went live in early February, backed by three major banks.

The London Stock Exchange (LSE.LN) has its own dark pool effort called Baikal in the works, which was delayed following the collapse of Lehman Brothers (LEHMQ), the LSE's partner in the venture.

The U.S. brokerage Knight Capital Group (NITE) and Pipeline, a New York-based dark pool operator, also have European platforms set to launch this year.

Neuro Dark, which awaits regulatory approval from the U.K. Financial Services Authority, will operate on the same technology powering Nasdaq OMX's European multi-lateral trading facility Nasdaq OMX Europe.

Trades will be cleared through the European Multilateral Clearing Facility; Nasdaq OMX bought a 22% stake in the clearinghouse in early February.

Dark pools have been a small portion of overall European equities trading, with late 2008 estimates putting their market share at less than 1% of executed trades.

-By Jacob Bunge, Dow Jones Newswires; 312-750-4117; jacob.bunge@dowjones.com