SoftBank $SFTBY ( ▼ 0.55% ) has fully funded its $40 billion investment in OpenAI, officially overtaking Microsoft $MSFT ( ▲ 0.08% ) as the startup’s largest financial backer, according to CNBC. The final tranche of roughly $22 billion was sent last week, completing a deal that had been structured to roll out over 12 to 24 months and was contingent on OpenAI transitioning to a for-profit public benefit corporation, which it completed in September.
What This Changes for OpenAI and Microsoft
While SoftBank now sits at the top of the cap table, Microsoft remains deeply embedded in OpenAI’s business. Its roughly $13 billion investment translates to an estimated 27% stake at valuations cited as high as $830 billion, and it retains exclusive cloud and commercial licensing rights through Azure. In practice, this means Microsoft still controls key distribution and infrastructure channels even as SoftBank provides the largest pool of capital.
Why SoftBank Is Doubling Down on AI Infrastructure
The investment fits squarely into SoftBank’s renewed AI-first strategy. Some of the capital is expected to support OpenAI’s massive infrastructure buildout, including the Stargate joint venture with Oracle $ORCL ( ▲ 0.94% ) and SoftBank itself. OpenAI has already lined up more than $1.4 trillion in long-term infrastructure commitments, spanning chips from Nvidia $NVDA ( ▼ 0.36% ) , Advanced Micro Devices $AMD ( ▼ 0.07% ) , and Broadcom $AVGO ( ▲ 0.15% ) , alongside data center and connectivity expansions.
Notably, SoftBank recently sold its entire Nvidia stake and agreed to acquire data center investor DigitalBridge $DBRG ( ▲ 0.13% ) for $4 billion, signaling a shift from public AI beneficiaries toward owning the physical and financial backbone of the AI economy. Together, these moves position SoftBank less as a passive investor and more as a central architect of the next phase of AI infrastructure.