Fiat Spa Chairman Luca Cordero di Montezemolo will announce his retirement later today, the company confirms.

Although Fiat has not named a replacement, speculation is John Elkann, the great-great grandson of Giovanni Agnelli, one of the founders of Fiat in 1899, will take the post.

The decision to replace Montezemolo comes a day before Fiat Automobiles SpA CEO Sergio Marchionne is set to disclose the next 5-year business plan, which is expected to include spinning off Fiat’s auto operations from parent Fiat SpA, possibly by year’s end.

The spin-off is seen opening the door for additional alliances with other auto makers and providing the funding needed for international expansion.

A statement issued by Fiat says Montezemolo has decided this is a good time to step aside, because he believes he has “completed the assignment given to him by the core shareholder in May 2004.”

Montezemolo will remain a member of the Fiat board and stay on as chairman of Ferrari, Fiat says.