It's no secret that Sony's mobile division has been struggling for years. Every quarter, the financials consistently show losses under the Mobile Communications section, and the Q4 2018 and FY2018 results are no different. That said, the mobile division is an outlier, as Sony as a whole is still profitable.
Sony generated a total of 82.7 billion yen ($741 million USD) in operating income in the fourth quarter of last year, up drastically from Q4 2017's 22.2 billion yen ($199 million). For the full year of 2018, there was 894.2 billion yen ($8 billion) in operating income, up from 734.9 billion yen ($6.6 billion) for the year of 2017. It's clear that Sony as a whole is doing quite well, though the same can't be said for the mobile division.
The company shipped 6.5 million smartphones in 2018, a whopping 50% decrease from 2017's 13.5 million shipments. The Mobile Communications segment of Sony lost 41.1 billion yen ($368 million) in Q4 2018, which is a bit better than the 44.6 billion yen ($400 million) loss from Q4 2017. What we're really interested in here, though, are the FY2018 mobile numbers, and those are disappointing to say the least. While Sony's 27.6 billion yen ($247 million) loss in mobile in 2017 was already unfortunate, the 2018 loss of 97.1 billion yen ($870 million) is far worse.
For now, Sony's other divisions, especially the gaming and music teams, are sustaining its losses in mobile. Whether or not it can continue to justify said losses, however, is another story.