A surge in option market bets on Sony just before a large hedge fund investor announced a big stake and called for a major restructuring of the company has raised concerns that some traders may have had advance word of the news.

US-listed shares of Sony jumped 9.9 per cent to close at US$ 20.76 after Daniel Loeb’s Third Point hedge fund said on Tuesday it accumulated more than 6 per cent of Sony’s shares – a stake worth US$ 1.1 billion – making it the largest shareholder in Japan’s biggest electronics company.