Toto Wolff is the new executive director of the Mercedes F1 team and has joined Niki Lauda in acquiring a stake in the company.
Wolff, who also has shares in the Williams F1 team, stepped down from his position with the Grove-based outfit on Monday morning to take up a role at Mercedes.
The new job will see Wolff take over complete co-ordination of all Mercedes-Benz motorsport activities while also becoming a shareholder in the F1 team.
"Mercedes is one of the most important participants in motorsport worldwide," said the 41-year-old. "I am not only a big fan, but also a longstanding friend and enthusiast of the brand.
"I am looking forward to the challenge and, along with preparing for a successful racing season, also want to focus on the targeted promotion of new talent."
He added: "I am leaving Williams on good terms and I will miss the team and friends I have made there. I'd also like to wish Frank and the whole of Williams the best of luck for the future."
Dr Dieter Zetsche, Head of Mercedes-Benz Cars and Chairman of the Board of Management of Daimler AG, has welcomed Wolff's arrival.
"As an entrepreneur, investor and motorsport manager, Toto Wolff has proven that this sport runs in his blood; at the same time, he is also well aware of the economic necessities of the business.
"With Toto Wolff, we have gained for our Formula 1 team not only an experienced motorsport specialist, but also a longstanding enthusiast of the Mercedes-Benz brand. Together with him and Niki Lauda, we will further develop our motorsport activities and guide our Silver Arrows into the next era."
Toto Wolff leaves Williams