Mercedes motorsport head Toto Wolff has sold his remaining stake in the Williams Formula One team to US shareholder and healthcare executive Brad Hollinger, both parties said on Wednesday.
The family's departure marks the end of an era after 43 years and 739 Grands Prix.
Williams have vowed to be more aggressive in Sunday's Malaysian Grand Prix after scoring points with both cars in Bahrain's season-opener.
Australian Sam Michael took over from Patrick Head as Williams technical director in a restructuring accelerated by the Formula One team's disappointing start to the season.
Germany's Ralf Schumacher earned plaudits after putting Williams back on the podium in his penultimate race.
Bookmakers William Hill have the Briton as 15/8 favourite for the 2018 drivers championship, with Ferrari's Sebastian Vettel at 3/1 and Red Bull's Max Verstappen at 10/3.