European exchanges face an uphill struggle to meet an important deadline by the end of this week to agree the next stage of reforms to clearing and settlement, in a move that could provoke a backlash from the European Commission in the form of tougher regulation.

They have until Saturday June 30 to agree the terms under which clearing and settlement organisations offer "interoperability and access" to each other and to market users, in an attempt to break down so-called "vertical silos" under which exchanges own and control the trading, clearing and settlements systems in individual markets.