His sudden resignation, which comes before a long-term succession plan has been decided, marks a dramatic exit for a man who had been tasked with righting the automaker following the arrest and ouster of former chairman Carlos Ghosn last year on charges of financial misconduct, which Ghosn denies. Saikawa, a protege of Ghosn, took over as Nissan CEO from his mentor in 2017, leaving Ghosn as chairman. His brief tenure has been characterised by strain with top shareholder Renault SA and tumbling profit. Nissan's shares have lost almost a quarter of their value this year. The worsening relationship with Renault has been a particular concern for investors and has cast doubt on the future of the Franco-Japanese automaking alliance at a time of sweeping change and uncertainty in the global auto industry.