TOKYO (Reuters) -Japan's SoftBank Group reported on Tuesday a net profit of 2.5 trillion yen ($16.6 billion) for the July-September quarter, its third consecutive quarter of profits.

That compared with a net profit of 1.18 trillion yen in the same period of the previous year. Three analysts surveyed by LSEG had estimated on average a net profit of 207 billion yen for the current year's quarter.

SoftBank's Vision Fund unit posted an investment gain of 3.5 trillion yen, primarily deriving from the group's holding in ChatGPT creator OpenAI which totalled 2.16 trillion yen for the quarter.

The results coincide with a bull run in technology-related stocks that has sent SoftBank's share price to record highs.

As the wave of investment in artificial intelligence infrastructure such as data centers continues apace and frontrunners in AI development such as OpenAI project rapid growth, SoftBank has been a major beneficiary.

Nevertheless there are growing concerns among investors of an "AI bubble", whereby the enormous sums committed to capital investment by leading firms may not generate the high profits to justify the investments.

($1 = 150.7800 yen)

(Reporting by Anton Bridge; Editing by Tom Hogue and Muralikumar Anantharaman)