New | Revamp lies behind Sony's dramatic share price rise

Newfound enthusiasm for Sony seen in a surging share price owes much to chief executive Kazuo Hirai's November 2013 decision to elevate someone from the internet services unit to push through painful changes.

Four months later, Kenichiro Yoshida went from relative obscurity to become Hirai's right-hand man and chief financial officer. The 55-year-old has used the mandate to cut jobs, sell off Sony's iconic Vaio personal-computer business, spin out its television unit and rein in the company's destructive market share ambitions in smartphones.

"He started the most important thing that Japanese companies cannot do - exit," said Atul Goyal, a Singapore-based analyst at Jefferies Group.

"If you remove Yoshida, this stock is no longer a buy. It's probably a sell."

Yoshida's focus on restructuring, including the US$1.5 billion write-down of its smartphone business, has cut costs and stemmed losses in consumer electronics.

His actions have helped restore credibility with investors for a company that lowered its earnings outlook 15 times in the past seven years.