The axe has fallen on Carlos Ghosn – the Nissan Motor chairman was arrested on Monday for alleged financial misconduct and will be fired from the board this week, media reports from Japan said.

Reuters noted it was a dramatic fall for a charismatic leader hailed for rescuing the Japanese automaker from close to bankruptcy.

Ghosn is also chairman and chief executive of Nissan French partner Renault, and one of the best known figures in the global car industry, and his departure will raise questions about the future of the alliance, the news agency said.

Nissan said an internal investigation, triggered by a tip-off from a whistleblower revealed Ghosn engaged in wrongdoing including personal use of company money and under reporting for years how much he had been earning.

Nissan CEO Hiroto Saikawa was reported as saying too much power had been concentrated on Ghosn, a rare foreign executive who enjoyed corporate superstar status in Japan for reviving the ailing Japanese brand.

“Looking back, the concentration of power was something we need to deeply reflect on,” he said, confirming the arrest of Ghosn in Japan.

According to Reuters, Saikawa said he could not give specifics on the personal use of company money, but said that the wrongdoing was serious and unacceptable and had gone on for years.

“To have so greatly violated the trust of many, I feel full of disappointment and regret,” Saikawa told a news conference in Tokyo.

“It is very difficult to express this…. It’s not just disappointment, but a stronger feeling of outrage, and for me, despondency.”

French president Emmanuel Macron said the government, the French carmaker’s top shareholder, would be vigilant about Renault and its alliance with Nissan.

Saikawa said he would propose at a board meeting on Thursday to remove Ghosn and representative director Greg Kelly.

Reuters said Renault shares fell 11% in Paris to be among the worst performing stocks in Europe. Nissan’s German-listed securities fell 10%.

The news agency said Ghosn, known as ‘Le Cost Killer’ for overseeing turnarounds including cuts at Renault, had remained popular in Japan despite the massive job cuts that he brought and recent controversy over his lucrative pay package.

Japanese media reported that he had reported around JPY10bn of annual compensation as around JPY5bn for several years.

Reuters speculated that Nissan’s ousting Ghosn was bound to raise questions about an alliance that he personally shaped and had pledged to consolidate with a deeper tie-up, before eventually stepping back from its operational leadership.

“The initial share price reaction shows how pivotal he is,” Citi analyst Raghav Gupta-Chaudhary said.

The current alliance structure had long undervalued Nissan shares held indirectly by Renault investors, he added.

“Ghosn is viewed as critical for value unlock,” Gupta-Chaudhary told Reuters

Renault owns 43.4% of Nissan, while Nissan owns 15% of Renault, with no voting rights in a partnership that began in 1999. Since 2016, Nissan has also held a 34% controlling stake in Mitsubishi Motors following a scandal in which the latter falsified fuel economy data, leading to the recall of its own and Nissan branded minicars supplied on an OEM basis.

Reuters said the news was likely to raise questions about Nissan’s accountability at a time when Japan has been pushing companies for better governance.

“The problem of governance was significant,” Saikawa said.

The Asahi newspaper had reported earlier prosecutors had begun searching the offices of Nissan’s headquarters and other locations on Monday evening.

In June, Renault shareholders approved Ghosn’s EUR7.4m (US$8.45m) compensation for 2017. On top, he received EUR9.2m in his final year as Nissan chief executive.

Earlier reports: Japanese prosecutors questioning Ghosn on salary

Nissan to remove Ghosn from post following ‘misconduct’ investigation