Nasdaq OMX and LCH.Clearnet have agreed a share deal that involves the U.S. exchange taking a stake in the latter in return for LCH acquiring a Nasdaq-owned clearing house.

London Stock Exchange takeover target LCH said in an emailed statement on Tuesday it had agreed non-binding terms to acquire International Derivatives Clearing Group (IDCG), Nasdaq's specialist U.S. swaps clearing house.

Neither party disclosed terms or predicted when the deal might close.

The IDCG deal is potentially significant for the London Stock Exchange (LSE) as it strengthens LCH's strong franchise in over-the-counter (OTC) derivatives, where LCH's Swapclear is the market leader for interest rate swaps, the largest OTC market.

The LSE wants to buy LCH to position itself ahead of OTC regulatory changes. It said last month it wants to take up to 60 percent of LCH, offering shareholders 20 euros per share and valuing the target at 813 million euros (669.39 million pounds).

The LSE declined to comment on the IDCG deal.

The IDCG deal is designed to make LCH's Swapclear more attractive in the U.S., said Richard Perrott, an analyst at Berenberg Bank.

Perrott estimates Nasdaq may take about 2 percent in LCH, based on the value of IDCG when Nasdaq bought it in 2008.

That would make Nasdaq the third-largest exchange shareholder in LCH, after hometown rival NYSE Euronext , with 9 percent, and the London Metal Exchange which has 8 percent.

The precise shareholder breakdown is dependent on the LSE's bid to buy a majority stake in LCH, which the British exchange expects to close in the fourth quarter of this year.

Swapclear is seen by analysts as a prized asset given regulators in the United States and Europe are keen to introduce, as soon as next year, rules to force vast swathes of the $700 trillion (433.86 trillion pounds) over-the-counter markets to use clearing.

This strategic acquisition would complement our U.S. offering, where we are seeing accelerating client take-up for the Swapclear service, said Swapclear Chief Executive Michael Davie.

Clearing houses work to cut the risk of trading on exchanges by guaranteeing each side of the transaction, minimising losses for members if a counterparty goes bust.

(Editing by David Hulmes)