SoftBank’s blockbuster bet on OpenAI is no longer a promise, it’s paid in full. On December 31, 2025, SoftBank confirmed it completed the final (second) closing of its investment, satisfying a commitment of “up to $40.0B” that was originally agreed in late March 2025.
The announcement caps a year defined by mega-rounds, AI infrastructure ambition, and intense competition among foundation-model leaders. With OpenAI’s funding widely framed as the largest private tech raise on record, the details, timing, syndication, ownership, and what happens next, matter as much as the line number.
The deal in one line: SoftBank’s $40B commitment is fully funded
SoftBank said it completed the final closing by investing an additional $22.5B, executed on December 26, 2025 (U.S. time). With that second payment, SoftBank stated its March 31, 2025 commitment to invest “up to $40.0B” is now fully satisfied.
Reuters similarly reported that SoftBank has “fully funded” the $40B investment, describing a final tranche of roughly $22B to $22.5B and noting the deal was initially agreed in March 2025. The alignment between SoftBank’s press disclosures and Reuters’ reporting helps clarify the end-state: the capital has moved, and the round is no longer contingent on future closings.
SoftBank also disclosed the resulting stake: an “aggregate ownership interest” of approximately 11%. For a company reportedly valued around $300B post-money at the time the round was described as closed, that percentage underscores both the scale of the check and how large OpenAI’s capitalization has become.
Two closings, one strategy: April first, December final
The structure was staged from the start. In an April 1, 2025 press release, SoftBank laid out a schedule: $10.0B targeted for mid-April 2025 (planned), and up to $30.0B targeted for completion by December 2025 (planned). That timetable foreshadowed the two-step execution later confirmed at year-end.
In its December 31, 2025 update, SoftBank said it invested $7.5B at the first closing (April 2025) and $22.5B at the second closing (December 2025), both via Vision Fund 2. The April amount being $7.5B, rather than the earlier “$10B planned” figure, highlights how syndication and final allocation can shift even when line commitments remain constant.
This staged approach also matches earlier reporting that anticipated payouts over 12 to 24 months. The practical benefit is flexibility: it gives the lead investor room to manage financing, bring in co-investors, and coordinate with the recipient’s capital needs and milestones.
Syndication and the twist: the round was “upsized” with $11B of co-investors
One of the most significant year-end details is that the financing expanded beyond the line SoftBank commitment. SoftBank disclosed “oversubscribed and upsized” co-investor participation of $11.0B, bringing the “final aggregate commitment” funded to $41.0B.
That figure is important for two reasons. First, it signals continued appetite for OpenAI exposure even at the valuation levels reported in late March 2025. Second, it shows how mega-rounds often operate in practice: a lead investor anchors terms, while additional demand can increase total proceeds or reshape allocations.
Back in April 2025, SoftBank said it intended to syndicate out $10.0B and described its “effective investment” as expected to be up to $30.0B. The December disclosure, $11.0B of co-investors and $30.0B funded by SoftBank across two closings, lands very close to that blueprint, with the notable difference that demand apparently exceeded the initial syndication target.
Valuation context: why $40B made lines worldwide
When the round was reported as closed on March 31, 2025, CNBC said OpenAI raised $40B at a $300B valuation (including new capital), with $30B attributed to SoftBank and $10B to a syndicate that included Microsoft and others. Bloomberg likewise reported OpenAI finalized $40B at a $300B valuation, and noted PitchBook data describing it as the largest funding round of all time.
The numbers stand out not only because they’re large, but because they reset expectations for late-stage private financing in AI. The combination of massive capital needs (compute, talent, product scaling) and massive demand (enterprise adoption, consumer subscriptions, platform partnerships) has created conditions where “venture rounds” begin to resemble sovereign or infrastructure financings.
Earlier in 2025, the valuation framing evolved in public reporting, CNBC cited discussions around $260B pre-money and $300B post-money, while even earlier reports floated higher “up to” valuations during talks. The final narrative converged around the $300B post-money figure, emphasizing how quickly terms can crystallize once a lead investor commits at scale.
How SoftBank financed and routed the investment
SoftBank’s April 1, 2025 press release provided a rare look at the plumbing behind an investment of this size. It said the April 2025 $10.0B payment was expected to be financed through borrowings, including Mizuho Bank, excluding any syndicated amount. In other words, the commitment was backed by concrete financing plans, not just intent.
By December 31, 2025, SoftBank clarified that both closings were executed via Vision Fund 2. This matters because it indicates where on SoftBank’s balance sheet and investment platform the exposure sits, and it shapes how SoftBank reports performance, risk, and liquidity associated with the stake.
The end result is a layered structure: SoftBank as lead, Vision Fund 2 as primary vehicle, financing support for early tranches, and co-investors to share exposure. That blend is increasingly common in mega-deals where the lead wants strategic influence and upside, but also wants to manage concentration risk.
What the ~11% stake could mean for governance and influence
SoftBank’s disclosure of an aggregate ownership interest of approximately 11% gives a clearer signal about its positioning. It suggests meaningful economic exposure, large enough to matter, but not so large as to imply outright control in a company with a complex stakeholder landscape.
In practice, minority stakes of this size can still translate into influence: board-level visibility (depending on terms), strategic partnership discussions, and alignment on long-term infrastructure plans. The real leverage often comes from being a reliable capital provider during periods when AI leaders must continuously reinvest in compute and model development.
It also creates reputational coupling. SoftBank’s brand and Masayoshi Son’s long-standing thesis-driven approach become more tightly linked with OpenAI’s trajectory, product success, safety posture, regulatory relationships, and the broader debate about how advanced AI should be built and deployed.
Infrastructure and ambition: linking the funding to a broader AI push
Reuters framed SoftBank’s OpenAI funding as aligned with a broader AI infrastructure push, referencing the “Stargate” data-center initiative context. While specific project economics can be complex, the strategic logic is straightforward: leading AI models require enormous compute, and compute increasingly resembles infrastructure.
The Guardian captured the philosophical framing with a quote attributed to Masayoshi Son: “AI is a defining force shaping humanity’s future…”. That line reflects why this isn’t treated as a typical late-stage tech investment, SoftBank is positioning AI as a civilizational platform shift, worthy of outsized capital commitments.
If the AI arms race is partly a race for reliable access to chips, power, and data-center capacity, then a $40B-scale investment can be read as both a balance-sheet bet and a strategic move. It supports OpenAI’s growth while reinforcing the ecosystem needed to run frontier models at global scale.
With the second closing complete and the commitment fully satisfied, the story shifts from “will it fund?” to “what will it fund?” SoftBank’s year-end confirmation, plus disclosure of $11B in co-investor participation pushing total funded commitments to $41B, turns the 2025 mega-round from line into settled fact.
For OpenAI, the funding provides oxygen for compute-heavy roadmaps and aggressive product expansion. For SoftBank, the roughly 11% stake crystallizes a defining wager on the AI era, one that ties financial returns to the pace of AI adoption, the economics of infrastructure, and OpenAI’s ability to maintain leadership in an increasingly crowded field.
