The private equity partners of both firms announced the shock move on Monday.
Permira and CVC bought the AA for £1.7bn in 2004, while Charterhouse acquired Saga for £1.35bn in 2005. The deal sees Permira and CVC own 42.5% of the business, Charterhouse 37.5% and the management and staff of both businesses the remaining 20%.
AA chief executive Tim Parker has announced he will step down from the post. A statement said: “Tim Parker has signalled his intention to pursue new business projects outside the AA once the transaction is completed.”