Porsche today said it has raised its stake in Volkswagen group to 35 percent from 31 percent.
It said VW is now a subsidiary of Porsche Automobil Holding under German law.
Porsche also said it is required by law to submit a formal mandatory offer for VW subsidiary Audi as a result of the new shareholder structure.
Porsche CEO Wendelin Wiedeking said the sports car maker has no interest in separating Audi from VW group.
"We see Audi as an integral part of VW group and have no interest in taking the company out of the group," Wiedeking said in a statement.
Porsche said its takeover offer for Audi will be at the minimum price of about 487 euros per share.