SoftBank to lead $40 billion OpenAI funding round at $300 billion valuation
On April 1, SoftBank Group Corp. announced it would lead a funding round of up to $40 billion in OpenAI at a post-money valuation of $300 billion, the largest single investment ever made in a privately held technology company, according to the SoftBank press release and reporting by Reuters and the Financial Times. The round closes in two tranches: an initial $10 billion in April and up to $30 billion by December, the second tranche conditional on OpenAI completing its restructuring into a for-profit entity.
The deal is the largest concrete step yet in the strategic alignment between SoftBank and OpenAI announced earlier in 2025. In January, the two companies — together with Oracle and MGX — disclosed the Stargate joint venture, a $500 billion data-center commitment over four years. Masayoshi Son, SoftBank's chairman and chief executive, has positioned OpenAI as the central partner in his stated mission to bring about Artificial Super Intelligence, and the April round provides the equity component to back that operating commitment.
In SoftBank's official statement, Son said: "AI is a defining force shaping humanity's future. Our expanded partnership with OpenAI accelerates our shared vision to unlock its full potential." OpenAI separately confirmed the round in company materials and on X, with chief executive Sam Altman framing the new capital as the basis for substantially deeper compute commitments and continued research expansion.
SoftBank's effective contribution is up to $30 billion; the company plans to syndicate $10 billion to co-investors, Reuters reported. The initial $10 billion tranche is being financed through borrowings led by Mizuho Bank, according to the SoftBank disclosure and Wall Street Journal reporting. If OpenAI does not complete its for-profit restructuring by the end of 2025, the December tranche reduces from $30 billion to $10 billion, capping the round at $20 billion. The $300 billion post-money valuation is roughly double OpenAI's October 2024 mark of $157 billion.
Reaction in financial markets was mixed. SoftBank's Tokyo-listed shares traded sideways in the days following the announcement; analysts at Bernstein and Jefferies, quoted by Reuters and the Wall Street Journal, noted the heavy reliance on debt financing and the open question of whether OpenAI's restructuring will clear regulatory and Microsoft-related contractual hurdles before December. Several US AI investors, speaking to the Financial Times, described the round as a signal that foundation-model leadership is now a function of bilateral capital pacts rather than venture syndication.
For us at Enpo Sekai, the main reading from the round is structural rather than competitive. A $40 billion equity raise, financed in part by bank debt and gated on a corporate restructuring, is a model-layer event — the kind of capital that buys compute years, not the kind that small studios can match or even meaningfully react to. Our work continues one layer above: characters, voice, and persona for desktop and games, where the differentiation is creative direction and product surface, not foundation training runs. The round does not change that calculation; it sharpens it.
We will be watching three things over the next twelve months: (1) whether OpenAI completes the for-profit restructuring on the December timeline, since that gating decision determines whether the round lands at $40 billion or stops at $20 billion; (2) how the Stargate compute build-out converts the equity into deployable capacity, and on what schedule; (3) how SoftBank funds and amortizes the Mizuho-led debt, since the answer materially affects the firm's ability to underwrite the next round of AI capex. None of these alters our roadmap, but each shapes the cost of the platform layer we build on.
