The proposed deal will create a European derivatives powerhouse. Advocates of the deal claim that the merged group provides ballast to the CME Group on the other side of the Atlantic and that competition from OTC trading and MTFs will prevent market dominance.

It appears that Joaquín Almunia, Commission Vice President in charge of competition policy, is not so sure. In yesterday’s statement, the Commission said it had “significant concerns” over the possibility of a “negative impact on impact on innovation in derivatives products and technology solutions”.

The Commission raised concerns over almost every aspect of the derivatives side of the deal, highlighting the possible reduction of fee competition, the vertical silo clearing model as well as “a number of other areas” including, crucially, index licensing.

Executives in Paternoster Square, the headquarters of the London Stock Exchange will welcome the statement. The LSE , through its derivatives platform Turquoise, is leading the charge for competition in the European derivatives market having launched with a whimper its FTSE 100 futures contract in June in direct competition with NYSE Liffe.

The cynical among us might speculate the contract was launched to prove that competition without fungibility was a chimera.

But the statement raises some interesting questions about what the ultimate result of the investigation might be. Outside an outright rejection of the deal, which remains unlikely despite yesterday’s statement, there are a number of possible requirements the Commission might force in order for the deal to proceed. These include:

1. A spin off of Eurex Clearing

2. A spin off of NYSE Liffe

3. A mandate to make trading on Stoxx and other index products fungible

4. Forced access to clearing for all parties

Points one, two and three may be too high a price to pay for the two companies and their shareholders (although ICE will be waiting in the wings if a Liffe spin off is proposed) and point four may be hard to enact.

There is a precedent here. In 2005, when Deutsche Börse and Euronext were competing for control of the LSE, a report by the UK Competition Commission suggested a number of requirements for the deal to proceed. By the time the report came out the deal was already dead in the water but the proposals are worth looking at.

In particular, in the case of Deutsche Börse, it suggested a divestment of Eurex Clearing, a requirement that Eurex Clearing not be used as the provider of clearing services to LSE, or a “set of behavioural commitments” to prevent it from denying access to competitors.

Mr Niederauer and Mr Francioni will argue that the world has changed since 2005 and the technological requirements needed to compete today require economies of scale that only the tie up can achieve. But it seems that Mr Almunia might well disagree. December 13, when the final report is released, will be an interesting day.