Nissan's financial troubles are "disappointing" but Japan's number three automaker is still "extremely profitable," Ghosn said in an interview with the London-based Financial Times published Monday.
Ghosn, who in 2005 become chief executive of Renault as well as Nissan, said it made sense for him to head both automakers.
"If I were running two independent companies with no synergies, it would be too much. These two companies have a lot in common (and) that's why I'm here," he was quoted as saying.
He said the move earlier this year to give up the running of Nissan's US operations had been long planned, adding, "It's not that I was overstretched."
Nissan, 44 percent owned by Renault, continues to struggle after suffering its first drop in annual profits last year under Ghosn, who was the first foreigner to head a major Japanese company and oversaw an impressive recovery.
Nissan reported last week that its net profits slumped for a third straight quarter, hit by higher costs and weak domestic sales, but it maintained its forecast for a recovery in earnings for the full year.
Ghosn indicated he was still open to a possible tie up with a major US automaker, after talks broke down last year on opening the Nissan-Renault alliance to ailing General Motors.
"Fundamentally I still think that expanding the alliance is a good strategy," he told the FT in an interview at Renault's head office in Paris.
