TOKYO - Sony on Monday announced plans to sell its entire holding in social networking firm DeNA, as the Japanese electronics giant offloads assets to help repair its tattered balance sheet.

The company said it would log a gain of about 40.9 billion yen (S$542.7 million) from the sale to Japan's top brokerage house Nomura Holdings. It did not immediately disclose the sale price.

Last week, Sony said it had sold one of its main buildings in Tokyo for $1.2 billion (S$15.9 million), as the maker of Bravia television and PlayStation game consoles eyes a net profit for the fiscal year to March, its first in four years.

Since January, Sony has also said it would sell its US headquarters in Manhattan for more than $1.0 billion (S$13.2 million) and book a $1.2 billion (S$15.9 million) gain from selling part of an online medical services unit.

The company has launched a massive corporate overhaul that includes thousands of job cuts, the sale of a chemical division and an investment in Olympus to tap the camera and medical equipment maker's strong foothold in the global market for endoscopes.

Last month, Sony announced it would launch its PlayStation 4 system as it faces increasing competition from cheap - or sometimes free - downloadable video games for smartphones and tablets.

Shares in the firm, which last year fell below 1,000 yen for the first time since the era of the Walkman, closed up 3.45 per cent at 1,438 yen in Tokyo trading.

Japan's electronics sector, including Sony rivals Panasonic and Sharp, has suffered myriad problems including a strong yen, slowing demand in key export markets, fierce competition especially in the struggling TV division and strategic mistakes that left its finances in ruins.