In a story that started out with Porsche trying to take over Volkswagen only to end up the other way around, VW made a significant step towards its plan to integrate the German sports car brand by announcing today that it acquired a 49.9% stake in Porsche AG’s car operations for €3.9 billion, which comes to about US$5.8 billion at today’s exchange rates.

“The acquisition of the trading business of Porsche Holding Salzburg is planned for 2011. The creation of the integrated automotive group is then to conclude with the merger of Volkswagen AG and Porsche SE during the course of the same year,” Volkswagen said in a prepared statement for the media on Monday.

The German automaker, which also owns the Seat, Audi, Skoda, Bentley, Lamborghini, Bugatti and Scania brands, said that it expects Porsche’s integration will lead to an increase of the VW group’s annual operating profit by around €700 million in the long term.

We remind you that Porsche initially tried to acquire the Volkswagen Group by amassing billions of euros in loans, but soon ran out of funding due to the economic crisis ultimately leading to the opposite result…