The acquisition will enable LCH.Clearnet to operate a US-domiciled clearing counterparty and offer an integrated mechanism for cross-product margining alongside New York Portfolio Clearing, DTCC and NyseEuronext.

IDCG will be renamed LCH.Clearnet LLC and is expected to launch in the fourth quarter 2012 subject to regulatory approvals.

Under the terms of the transaction, which has been under discussion since April, Nasdaq OMX gains a 3.7% stake in LCH.Clearnet at EUR19 per share.

Ian Axe, chief executive of LCH.Clearnet, says: "This transaction is a strategic move to expand our US footprint and provide clients with additional flexibility and choice. It underscores our continued commitment to a horizontal clearing model for a global marketplace."