Michael Andretti is to take sole charge of the Andretti Green Racing IndyCar Series team at the end of this season.
The former Champ Car champion's current partners Kim Green and Kevin Savoree have agreed with Andretti that they will separate from the racing team - which also has Indy Lights and A1GP programmes - to focus on the Andretti Green Promotions arm that runs the St Petersburg and Toronto street races.
"Since becoming partners in 2002, we have been fortunate to see our companies expand and diversify quickly and successfully," said a joint statement issued by Andretti, Green and Savoree.
"All of us believe that this decision will maximise the potential of both companies in the future."
Andretti indicated to the Indianapolis Star that the team's name is likely to change for next year, and added that the move to separate the two companies was driven by a belief that Andretti Green has become an unwieldy organisation.
"The reason we're doing it is, this thing is getting to be too big and too much," he told the newspaper. "It was distracting both sides.
"We just wanted to be responsible. 'You do this, I'll do this.' Both companies deserve 110 per cent because they're both great properties."
AGR was formed at the end of 2002, when Andretti became a partner in the Team Green organisation then run by Kim Green's brother Barry.
The renamed squad moved from Champ Car to IndyCar for 2003, and proceeded to win the 2004, 2005 and 2007 titles with Tony Kanaan, Dan Wheldon and Dario Franchitti respectively.
But AGR's four-car line-up has struggled to match Penske and Ganassi recently, and has not won a race since Kanaan's Richmond triumph in June last year.
Danica Patrick is currently AGR's leading contender in the championship in fifth place, but she is 139 points adrift of series leader Scott Dixon with four rounds remaining.