Hiroto Saikawa has overstayed his welcome at the wheel of Nissan Motor. He and other executives may have padded their pay, Reuters reported. The figures at stake appear small compared to allegations levied against ousted boss Carlos Ghosn, but that hardly matters. Saikawa has neither rebuilt credibility nor fixed performance at the $25-billion carmaker. Investors have no cause to remain patient.

Saikawa never won any popularity contests at Nissan. Still, some hoped he might serve as a decent caretaker after Ghosn was arrested, having been accused of financial misconduct by Japanese prosecutors. The Franco-Brazilian former chairman denies the charges, but the affair destabilized an already rickety relationship with alliance partner Renault.

Now, Nissan's audit committee has discovered Saikawa and other executives received excess stock-related compensation. Japanese media reported that Saikawa admitted as much, blamed it on "the Ghosn Era" and promised to pay it back. The results of the investigation are due to be presented to the board of directors on September 9.

The bad behavior is a full-body blow to Saikawa's authority, as he oversees an overhaul of Nissan's corporate governance. Investors might have been inclined to overlook it, had business been otherwise good. Unfortunately, he has repeatedly underestimated how bad things are. While he told investors in May that performance had hit "rock bottom," in July he proved it hadn't. Net income fell to just 6.4 billion yen ($59 million) in the three months ending in June, down around 95 percent from the same period the previous year, while operating margins fell from 4 percent to 0.1 percent.

Many of his strategic changes, meanwhile, have been questionable: Headcount reductions, for example, were nearly all in overseas markets that are growing faster than Japan is.

Nissan was supposed to return to the bond market to raise nearly 250 billion yen, a long-awaited sign of normalization. That has now been postponed, according to DealWatch.

In the immediate aftermath of the scandal, there was a case for letting Saikawa deal with the worst of the fallout, push through painful strategic changes in the US market, announce big layoffs and clear the way for a successor. For better or worse, that phase is complete. He has promised to resign once transition work is done: shareholders will hold him to that sooner rather than later.

The author is Pete Sweeney, a Reuters Breakingviews columnist. The article was first published on Reuters Breakingviews. bizopinion@globaltimes.com.cn