The 2007 merger of Suez and Gaz de France resulted in GDF Suez. The combination was completed on July 22, 2008, after the companies and the French government agreed on the structure of the deal.
Gaz de France was France’s historic natural-gas utility, while Suez was a diversified energy and infrastructure group with roots reaching back to the nineteenth-century Compagnie universelle du canal maritime de Suez. The merger created a large European utility active in gas, electricity and energy services.
The company was renamed GDF Suez in 2008, preserving both predecessor names. In 2015, it adopted the shorter name Engie as part of a rebranding intended to emphasize its broader energy activities and move beyond the historical “Gaz de France” identity.
This creates an important naming distinction: GDF Suez is the name produced by the merger, while Engie is the later corporate name. The answer to a question about the original merger is therefore GDF Suez.