* Q3 op profit Y2.6 bln vs Y438 bln year earlier
* Vision Fund Y225 bln yen loss vs Y176 bln yen profit year prior
* Vision Fund has invested $74.6 bln in 88 companies
* Vision Fund investments now worth $79.8 bln (Adds quote from Son, context)
By Sam Nussey
TOKYO, Feb 12 (Reuters) - SoftBank Group Corp reported a near-total wipe out in quarterly profit on Wednesday, after the Japanese technology investor was whiplashed for a second consecutive quarter by losses at its $100 billion Vision Fund.
The dire result is likely to deepen concern about founder Masayoshi Son's ability to secure funding for a second Vision Fund, and give more ammunition to activist investor Elliott Management which has recently emerged as a prominent shareholder.
The numbers are also the latest reminder of the inherent risk in Son's strategy of betting big on untested startups. The Vision Fund posted an operating loss of 225 billion yen ($2.05 billion) for October-December compared to 176 billion yen profit in the same period a year earlier.
But Son, who is known for his ebullience and charisma - still rare in corporate Japan - said his company was already turning the corner.
He pointed to a rally in prices at the Vision Fund's handful of listed investments and news overnight that a U.S. federal judge had rejected an antitrust challenge to the proposed merger of SoftBank's Sprint Corp and T-Mobile US Inc.
"The tide is turning," Son told a briefing following the release of SoftBank earnings.
Group profit reached 2.6 billion yen for the quarter versus 438 billion yen a year prior. The figure included a 332 billion yen dilution gain related to the secondary listing of portfolio firm Alibaba Group Holding Ltd.
The result compared with the 345 billion yen average of three analyst estimates compiled by Refinitiv. Analysts have said it is difficult to evaluate SoftBank's performance due to a lack of disclosure around Vision Fund's internal valuations.
The Vision Fund, which is backed by Saudi Arabia and has single-handedly changed the face of tech investing, said it had invested $74.6 billion in 88 companies as at December-end, at which time those investments were worth $79.8 billion.
Son's investing credentials took a hit in the August-September quarter when the Vision Fund recorded an $8.9 billion operating loss following weakness at major bets such as office space-sharing firm WeWork.
Since then, a slew of portfolio companies - from hotel-booking platform Oyo to cloud robotics firm CloudMinds - have cut jobs and come under pressure to demonstrate the long-term viability of their business models.
The fund itself has also lost key employees.
Tuesday offered a bright spot when a U.S. federal judge rejected an antitrust challenge to the proposed takeover of SoftBank's troubled U.S. wireless subsidiary Sprint Corp by T-Mobile US Inc, sending SoftBank stock to its highest price in seven months.
Nevertheless, SoftBank faces pressure to enhance shareholder value after sources told Reuters last week that U.S. hedge fund Elliott Management had amassed a stake of almost $3 billion in the conglomerate and is pushing for change including $20 billion in stock buybacks. ($1 = 109.8600 yen)
Reporting by Sam Nussey; Editing by Christopher Cushing and David Dolan