TOKYO - SoftBank Group Corp on Tuesday booked a net loss for October-December, with its giant Vision Fund investment unit staying in the red for the fourth straight quarter as tech portfolio valuations have yet to recover from a global sell-off.

The Vision Fund, which upended the world of technology with its big bets on startups, reported an investment loss of 730.36 billion yen ($5.52 billion) in the latest quarter. At SoftBank itself, the net loss totalled 783.42 billion yen, compared with a 29.05 billion yen profit a year earlier.

The net loss also marked a sharp turnaround from the 3 trillion yen profit SoftBank reported in the prior quarter, for July-September, when it was buoyed by the sale of some of its stake in China's Alibaba Group Holding.

SoftBank said the Vision Fund unit had "continued prudent defensive financial management" and it "significantly curtailed investments and continued to monetise investments" amid the challenging market environment.

The company's founder and chief executive, Masayoshi Son, invested heavily in artificial intelligence and other high-tech startups through the Vision Fund in recent years, delivering both record profits and heady optimism about future valuations.

But performance was battered by the global tech rout last year as rising interest rates, Sino-U.S. tensions and Russia's invasion of Ukraine prompted investors to drastically scale back on riskier assets.

Son, in turn, has cut back on investment activity.

($1 = 132.2200 yen)

(Reporting by Kiyoshi Takenaka; Editing by David Dolan and Jamie Freed)