SoftBank’s $64.6 Billion OpenAI Bet Ignites a $500 Billion Infrastructure Play

SoftBank gains from OpenAI-Anthropic valuation race, pours $64.6B into OpenAI, plans IPOs for SB Energy and Roze, and builds Stargate AI infrastructure.

The private-market valuation duel between OpenAI and Anthropic has become a powerful tailwind for SoftBank. Anthropic’s recent Series H round pushed its worth to $965 billion, leapfrogging OpenAI’s last communicated valuation of $852 billion. Every dollar added to those figures lifts the net asset value of SoftBank’s portfolio — and the stock has responded accordingly.

A $64.6 Billion OpenAI Stake

Over the fiscal year ending March 2026, SoftBank poured roughly $32.4 billion into OpenAI. Another $30 billion sits pledged, bringing the total commitment to about $64.6 billion in exchange for an estimated 13% stake. A potential IPO of the ChatGPT developer would crystallise those gains, even though OpenAI has recently missed some revenue and user-growth targets. Its infrastructure partnerships with Oracle and Amazon, valued in the hundreds of billions, nevertheless underpin the lofty valuation.

The biggest slice of that investment is tied directly to OpenAI’s upcoming public listing, which could dwarf most expected deals. SoftBank also holds a meaningful position in Arm, the chip designer that gained 16% over the same five-day stretch in late May.

From Chips to Power: The Infrastructure Layer

Masayoshi Son isn’t betting solely on equity stakes. The group is channelling capital into the physical backbone of artificial intelligence — electricity, data centres and construction capacity. The flagship project is Stargate, a $500 billion joint venture between SoftBank and OpenAI. It aims to build a network of AI-ready data centres, and a key operating unit will be SB Energy.

SB Energy owns or is building roughly 5 gigawatts of power generation, with a development pipeline exceeding 20 GW. In Texas it is constructing a 1.2 GW data centre campus that will run on solar and battery storage. OpenAI itself contributed $500 million to a separate joint investment with SoftBank in this area. Three AI data centres are already under construction.

Two Mega IPOs on the Horizon

SoftBank has formally mandated banks for two US listings. SB Energy, the energy and infrastructure arm, is targeting an IPO as early as September at a valuation north of $50 billion. JP Morgan, Goldman Sachs, Morgan Stanley, Citi and Mizuho are handling the deal.

The second offering involves Roze, a spin-off focused on autonomous robotics. Its goal: deploy robots to accelerate construction of large-scale AI infrastructure, addressing the labour and time bottlenecks that slow data-centre buildouts. SoftBank aims for a Roze valuation around $100 billion, which would rank it among the largest AI-adjacent listings ever.

Both IPOs represent more than portfolio optimisation. They are designed to turn the capital-intensive assets of the AI boom into publicly tradeable vehicles, allowing SoftBank to recycle capital while keeping a stake in the underlying growth story.

Japan’s Sovereign Cloud Ambitions

Alongside the offshore push, SoftBank is building a domestic AI cloud. The “AI Data Center GPU Cloud” — powered by NVIDIA GB200 and other cutting-edge chips — is scheduled for commercial launch in October 2026. An internal beta is already live. The platform runs on SoftBank’s proprietary “Infrinia AI Cloud OS”.

The move targets a clear market gap: Japanese enterprises handling sensitive data want sovereign processing options that US hyperscalers have so far provided only sparingly. SoftBank president Junichi Miyakawa called the platform strategically vital for Japan’s digital competitiveness. The company’s AI-RAN Alliance, led by Dr Alex Jinsung Choi, is also weaving AI into mobile network infrastructure.

Financing and the Holding-Discount Question

Book value looks sturdy. SoftBank reported net profit of $31.4 billion for the 2025 fiscal year, and its estimated net asset value stands at roughly $300 billion. To fund further expansion, it is preparing to issue hybrid bonds with a 35-year tenor worth around $1.6 billion. At the same time it is redeeming $669 million of senior notes maturing in July 2026.

The stock’s reliance on portfolio companies, however, keeps the holding-company discount in focus. Analysts caution that conglomerates often trade below the sum of their parts. “Sum-of-the-parts valuations typically justify a significant discount,” one assessment noted. Yet the majority still rates SoftBank a “Strong Buy.”

The stock closed up 4.6% in Tokyo on May 26, pushing its gain since May 20 to 40%. That rally lifted the market capitalisation past 40 trillion yen ($252 billion). With the 2026 IPO pipeline expected to test the market’s appetite for huge AI listings — including potential debuts from SpaceX, Anthropic and OpenAI itself — SoftBank is betting that its infrastructure twins can command those premiums even outside the group’s own balance sheet.