French company Eiffage has completed a deal to acquire the 49.99% stake in Aeroport Toulouse-Blagnac (ATB) previously held by China Airport Synergy Investment Limited (CASIL).

The agreement, negotiations for which had been under way for several months, was finally concluded on Dec. 30 Eiffage said that it paid “close to €500 million” ($558 million) for the stake. That would amount to a significant profit for CASIL, which paid €308 million for the stake in December 2014 as part of a French government sell-off of state assets.

The sale to a Chinese group was controversial at the time, as concerns were raised in several quarters over a wave of Chinese purchases of strategic Western infrastructure assets. Toulouse-Blagnac is the home of Airbus, whose final assembly buildings can be seen across the runway from the airport terminal.

Paris-based Eiffage is a large conglomerate with interests including construction, real estate, civil engineering and concessions.

ATB holds the concession to operate the airport—Frances fifth-largest, with a passenger throughput of 9.6 million in 2018—until 2046. Eiffage noted that it had regularly worked with ATB on projects in the past and that it intended to position itself as a long-term partner of the co-shareholders in developing the airport.

The company added that the acquisition fitted into its strategy of diversifying its concessions portfolio.