Sony Corp fell into a 91.7 billion yen (757 million pounds) operating loss in October-December, a disappointing result for the usually lucrative quarter that was worse than analysts' estimates as it battled a strong yen, Thai floods and a dull economy.
The company also forecast a full-year operating loss, hobbled by chronic losses in its TV operations despite restructuring efforts as it struggles to compete with aggressive South Korean rivals such as Samsung Electronics.
Sony's operating loss for its third quarter compared with an 8.8 billion yen average profit forecast of six analysts polled by Thomson Reuters I/B/E/S.
For the full year to March, the company forecast an operating loss of 95 billion yen, compared with the analyst consensus forecast of an 8.2 billion yen profit.
Sony announced on Wednesday that Vice President Kazuo Hirai, the designated heir apparent to CEO Howard Stringer, would take the president and CEO posts on April 1 in a long-awaited management succession.
Several Japanese technology companies, including Nintendo and Sharp Corp, have already surprised investors this earnings season with worse-than-expected earnings forecasts for the full financial year.
Panasonic Corp, also saddled with an ailing TV business and hit by the strong yen, will report its earnings on Friday.
The earnings announcement came after the end of trade on Thursday. Sony's shares have lost more than half their value over the past year, compared with a 15 percent drop in Tokyo's benchmark Nikkei average.
(Reporting by Nathan Layne and Yoko Kubota; Editing by Chris Gallagher)