Renault’s stock sunk to its lowest point in six years on Monday as worries mount about the potential unraveling of the company’s alliance with Nissan.

Investors are uneasy about the alliance’s future following Carlos Ghosn’s departure. Ghosn, who is evading Japanese authorities, has expressed doubts about the longevity of the world’s largest car alliance, labeling it a “masquerade” during a recent media briefing. The relationship between the French and Japanese automakers has always been fragile, reaching a tipping point in 2018 when Ghosn faced allegations of financial impropriety and was ousted as CEO. A report in the Financial Times on Monday revealed that Nissan executives are preparing a contingency strategy in case of a potential split between the two entities.

The disclosure of Nissan’s backup plans has triggered anxiety among investors. Renault’s shares tumbled over 3% on the Paris CAC 40 stock index on Monday. Despite recent efforts by senior figures at Nissan and Renault to display unity, the repercussions stemming from the allegations against Ghosn and his flight from Japan have led both firms to search for new leadership. While collaborative efforts are ongoing to chart a new course together, investors remain apprehensive as Nissan devises a fallback plan in case cooperative efforts falter.

Ghosn’s escape from Japan is the latest development in a series of conflicts between the two automakers. Renault’s unsuccessful attempt to merge with Fiat Chrysler in 2019 further strained relations.