Sony shares dropped the most in four years after reporting an eighth consecutive quarter of losses.

A 59 per cent jump this year by the maker of PlayStation game consoles helped drive the number of the shares being held in margin accounts to a 13-year high.

The accounts held 5.48 million shares as of yesterday, the most since March 2000, the data show.

Sony shares slumped 10 per cent to close at 1,365 yen, the biggest decline since November 2008.

The company's 150 billion yen ($1.6 billion) of convertible bonds due in 2017 fell the most since November, sliding 8.8 per cent to 147 yen per 100 yen in face value, according to Nomura Holdings.

"Speculators who have been rushing to buy Sony on expectation that the weakening yen will turn the earnings around must be disappointed," said Mitsushige Akino, Tokyo-based chief fund officer at Ichiyoshi Asset Management, which oversees about $356 million.

"They will close their positions to take profits or minimize losses."

Sony rebounded 92 per cent through yesterday from a 32-year low on November 15. Japan's exporters have rallied on speculation earnings will improve on the weaker yen, said Amir Anvarzadeh, a Singapore-based manager for Asia equity sales at BGC Partners.

The Japanese yen slid in the last four months, the longest streak of monthly losses since August 2008.

The currency has retreated about 14 per cent against the dollar since elections were announced November 14 amid speculation new prime minister Shinzo Abe would take aggressive steps to fight deflation.

"Some of the hedge funds have been accumulating long positions on the back of speculation that Sony will be turning things around," BGC's Anvarzadeh said.

"That quick, hot money is going to sell out. I don't believe Sony is going to turn around soon."

Unlike its rivals, the currency's weakness hasn't been enough to reverse Sony's losses.

Bloomberg