The news marks the sixth downward revision under Chief Executive Kazuo Hirai, who took his post in 2012 promising to pull the firm's troubled electronics division into the black by focusing on its mobile, gaming and imaging units.
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The revision is also an embarrassment for new Chief Financial Officer Kenichiro Yoshida, who assumed his post on April 1 promising the company would be more realistic about its outlook.
Yoshida warned in July Sony could write down losses on its mobile unit for this business year. At the time Sony cut its profit outlook for its smartphone business to zero, but stuck to its full-year forecast.
In July Sony also cut its full-year sales forecast for its smartphones to 43 million from 50 million, which would mark a 10 percent increase on the year.
Sales of Sony's high-end Xperia mobile devices have suffered due to a lack of relationships with carriers in the crucial U.S. market where its smartphones are so far only available on No.4 carrier T-Mobile US, as well as in China, where local makers are dominant.