TOKYO (Kyodo) -- SoftBank Group Corp. said Tuesday it posted a net profit of 1.01 trillion yen ($6.5 billion) for the six months to September, returning to the black for the first time in three years for the period, thanks to rising stock prices in its investment portfolio.

The earnings results are a major turnaround from a 1.41 trillion yen loss for the same period a year earlier when Softbank wrote down investments in startups.

"We have enough financial strength for various future investments in artificial intelligence," Chief Financial Officer Yoshimitsu Goto said at a press conference, adding Softbank has recently invested in OpenAI, the developer of the widely used AI chatbot ChatGPT.

In the first half, SoftBank posted 2.65 trillion yen in investment profit, thanks to the robust performance of its Vision Fund operations, whose cumulative investments returned to profitability for the first time in nine quarters in the June-September quarter.

The company, whose earnings are greatly influenced by stock market trends, had booked an investment loss of 963.6 billion yen in the same period last year.

The strengthening trend of the yen through September also boosted its profit by 289 billion yen in the six-month period, it said.

SoftBank benefited from a rise in the value of firms such as TikTok operator ByteDance Ltd., South Korean e-commerce giant Coupang Inc., and American telecom company T-Mobile US Inc., it said.

The tech conglomerate invested $500 million in OpneAi, Goto said, adding the deal is expected to contribute to the Japanese company's strategy revolving around AI.

"They are leading the global generative AI sector. We can learn a great deal from them," he said.

Expecting AI thousands of times smarter than humans to be within reach in a decade or so, SoftBank has been trying to increase its presence in the AI sphere through its British chip designer subsidiary Arm Holdings Plc. while ramping up investments in promising start-ups in the sector.

SoftBank Group's sales rose 7.5 percent to 3.47 trillion yen for the first half. The Japanese investment and technology group does not release an earnings forecast.