Uebber, 59, informed supervisory board chairman Manfred Bischoff that “he is not seeking to extend his current appointment,” Daimler said in a statement late Sunday. It didn’t provide a reason for the planned departure.

Uebber’s contract expires in December 2019. He joined Daimler’s management board in 2003 and took over responsibility for finance a year later.

The management change comes at a critical time for the world’s bestselling luxury-car maker and biggest producer of commercial vehicles by revenue. Uebber has been one of the key architects behind Daimler’s new group structure, which was created to give its cars, trucks and mobility-services units more independence. Shareholders are set to vote on the changes at the annual general meeting in May next year.

Daimler’s veteran CEO, Dieter Zetsche, last week defended the strategic logic behind the biggest corporate overhaul in a decade. He told reporters in Paris that the proposed revamp should boost efficiency and help to eventually turn around a stock slide that’s erased a fifth of the company’s value this year.

Investors have balked at the new structure and called for deeper changes, including separate listings of the trucks division or parts of the mobility-services operations. Daimler officials have denied plans for a complete divestment of any subsidiary but left the door open for a partial sale. The overhaul has also been criticized for its cost, earmarked at around 1 billion euros ($1.2 billion) and for having too little instant benefit to the company’s valuation.

Uebber was seen as a candidate to lead a holding company that bundles the three separate Daimler units. But the supervisory board’s decision last month to give Kallenius, 49, the same dual responsibility that Zetsche currently has as CEO and head of the Mercedes-Benz cars unit indicated this scenario was unlikely to materialize.