With the FOTA alliance crumbling, F1 chief executive Ecclestone announced on Saturday that he has agreed terms with the "majority" of teams.
In addition to the three top teams, it is believed Lotus, Toro Rosso, Sauber and Force India have also signed up.
I'm not sure who has signed.
That leaves Mercedes and Williams apparently yet to agree, while it is believed the three bottom teams Caterham, Marussia and HRT have not even seen a copy of the new Concorde Agreement.
Mercedes would not comment publicly.
"We would like to ask for your understanding that our team currently has nothing to say on this matter," said a spokesman.
Behind the scenes, however, high-level sources close to the Brackley based team admitted they are unhappy that the terms of the deal heavily favour the top three teams.
One bonus, for example, is for teams who have not changed their name.
Media outlets including PA Sport and London's Telegraph were told by the sources that the Stuttgart marque could challenge Ecclestone's methods against European Union competition law.
Or the carmaker and engine supplier could simply quit F1.
"It is understood the carmaker and parent company Daimler are prepared to play hardball", wrote Tom Cary in the Telegraph, referring specifically to European laws involving the abuse of a dominant position.
Other authoritative publications, also apparently briefed behind the scenes by Mercedes, referred specifically to the same laws.
On the record, Mercedes' competition vice-president Norbert Haug said in Malaysia: "I'm not sure who has signed. We've nothing currently to say."