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. Sony's shares climbed as much as 18 per cent in Tokyo on Thursday, the biggest jump on record since 1974, after the company reversed its forecast for a full-year operating loss. Hirai is shifting away from consumer electronics by focusing on image sensors, gaming and media content to rebuild earnings growth. The stock has surged 25 per cent this year, with the benchmark Topix index little changed, even as Sony deals with the fallout of a crippling computer hack on its Hollywood studio. Sony Pictures Entertainment said on Thursday that Amy Pascal, whose emailed jokes about US President Barack Obama became public in the cyberattack, will step down in May as co-chairman and head of its motion picture group. Yoshida, who likened restructuring to emergency surgery, plans to transform Sony into a company capable of generating a 400 billion yen (HK$26.4 billion) profit. He also wants more accountability. "Our reforms spared no sacred cows, whether at the main company or its units, and now you're beginning to see the results," Yoshida said after announcing the company's most profitable quarter in seven years. "We have an accountability to the outside world, something that we still need to work on, but the idea is beginning to sink in." "Yoshida gives an impression of a person who can execute," said Kazuyuki Terao, Tokyo-based chief investment officer of Allianz Global Investors Japan. "He doesn't just talk, but gets things done, and the numbers begin to show that."