Deutsche Boerse and NYSE Euronext have offered to cap fees on trading in their European derivatives contracts for three years in their last-ditch effort to get their $9 billion merger cleared by the European Union, according to Reuters.

The European Commission has expressed concerns that the two exchange operators' account for a 90 percent share of the exchange-listed futures market in Europe and could as a result thwart the arrival of new rivals.

"In addition to the submitted remedy proposal, both companies expressed their commitment to maintain the current level of their published standard fees for their European derivatives contracts for a period of three years," the exchanges said in a statement on Tuesday.

They said the offer was made in a letter to EU Competition Commissioner Joaquin Almunia.

Almunia told a news conference Tuesday that a decision on the deal could come by the end of January.

The exchanges face the risk of regulators blocking the merger if they are not convinced by the concessions.

NYSE Euronext and Deutsche Börse last week stepped up their proposal to divest assets in their derivatives businesses, in their effort to win clearance from European regulators for their merger.

The two exchange operators told the European Commission’s Directorate-General for Competition they would increase the assets to be divested and to provide the purchaser of the divested part of its derivatives business with an option to access Eurex Clearing for single equity derivatives products.

Tom Steinert-Threlkeld writes for Securities Technology Monitor.