Though DIC did not disclose the size of its Sony investment, speculations put it in the range between one to three per cent stake. What is definite is that it can't be more than 5 per cent as a listed company is required to report the stake to regulators within five business days.

In July, DIC expressed its interest to buy stakes of up to $1.5 billion in one or two publicly listed companies in Japan.

A $1.5 billion investment would be the equivalent of a 3 per cent stake in Sony, which has a market value of 5.52 trillion yen ($50.9 billion).

The recent purchases by DIC, which manages about $12 billion of assets, include the German-based specialty aluminum products company Almatis and a 9.9 percent stake in the United States hedge fund Och-Ziff Capital Management.

52.6 percent of Sony is already owned by foreign investors by the end of September.

Dubai has shown interest in the media and entertainment sector.