Volkswagen AG’s top two managers are being probed over allegations of market manipulation, deepening the carmaker’s legal woes in connection with the diesel scandal.

CEO Matthias Mueller and Chairman Hans Dieter Poetsch -- along with former CEO Martin Winterkorn -- are being investigated by Stuttgart prosecutors over whether they were too slow in telling Porsche SE shareholders about VW’s emissions cheating, said a person familiar with the matter, who asked not to be identified.

Porsche owns the majority of VW’s voting stock, and the men at the time had dual roles at the holding company and Volkswagen.

Poetsch, Winterkorn and another executive at the automaker are already being investigated in a separate German probe over possible manipulation of VW stock linked to the crisis. VW is facing a barrage of investigations, damage claims and customer complaints around the world after admitting in September 2015 that it rigged 11 million diesel vehicles to cheat on emissions tests. The scandal has cost it 22.6 billion euros (US$24.6 billion) in fines and other expenses so far, and the final tally remains unclear.

A VW spokesman declined to comment, while a Porsche SE representative said he had no information about the probe. A spokesman for Mueller said he was not aware of the investigation. Lawyers for Poetsch and Winterkorn didn’t immediately reply to e-mails seeking comment.

“We believe Porsche SE fulfilled its obligations to comply with capital market rules,” said Albrecht Bamler, a spokesman for the holding company.

The Stuttgart probe comes after a complaint last summer over the matter from German financial regulator Bafin.

The Stuttgart probe was first reported by German publication WirtschaftsWoche.

By Karin Matussek and Dalia Fahmy