The transaction contracts were signed by Atel, EOS and a consortium of minority shareholders of Atel and EDF on December 18.
The chairman of the board elect will be Hans Schweickardt, the chief executive of EOS, and the designated chief executive Giovanni Leonardi, current head of Atel.
Alpiq will have two main divisions, Energy and Energy Services with a total power station output of 5,270 MW. The operational start date is February 1.
Alpiq will supply around a third of Switzerland's electricity