Why predict Eurex as a survivor and not Deutsche Boerse?

This recent TowerGroup report makes some interesting predictions, and has sound reasons for picking its five suvivors in the global exchange land grab. On one hand I can see why they have picked Eurex as one of them, as its global strength as a derivatives exchange operator means it's the only real competitor for CME Group in this area.

But why list it rather than its co-parent companies, exchange operators  Deutsche Boerse (DB) and SWX Swiss Exchange? Sure, Eurex has 100% ownership of the International Securities Exchange, which has boosted its US derivatives presence as well as adding trading in US listed common stocks. But where does Eurex's revenue ultimately end up?

Ownership of Eurex is split 50/50 between its parents, but Deutsche Boerse receives 85% of Eurex revenues, which amounted to nearly €600 million in 2006. In 2006 this amounted to 32% of the Deutsche Boerse Group's total – second among the group’s five operating structures to clearing and settlement house Clearstream, which delivered 38% of group revenues.

At the beginning of the TowerGroup report, it mentions Deutsche Boerse's significant market capitalisation - at approximately $35 billion, the highest among the exchange groups it discusses. So I'm not sure why they picked a particular part of the group's organisational structure as one of its five winners, without discussing in more detail the German exchange operator's business in its entirety.

I tried contacting the report's author today, as I'm interested in asking this question. I'll keep you posted.