Nvidia's $5B Safe Superintelligence Bet Leads Week's Biggest Startup Funding Rounds

The Week's Biggest U.S. Startup Rounds: AI and Energy Dominate

Crunchbase's weekly tally of the largest U.S. startup rounds put a reported $5 billion Nvidia investment in Safe Superintelligence at the top of the list. Nvidia and the AI lab, founded by OpenAI co-founder Ilya Sutskever, announced a long-term partnership, with the capital earmarked to expand Safe Superintelligence's compute resources. The ten largest rounds announced in the U.S. over the past week totaled roughly $8.2 billion.

Energy technology accounted for three of the ten names and almost $1.9 billion of the total. Commonwealth Fusion Systems, a Massachusetts fusion startup developing a grid-scale power plant, raised $1 billion from unspecified investors, lifting lifetime funding to $4 billion. Antora Energy closed a $550 million Series C, co-led by G2 Venture Partners and Eclipse, to supply thermal batteries to data centers. Antares, a three-year-old nuclear fission company building compact microreactors for defense and space, raised $370 million in Series C equity led by Paradigm and Caffeinated Capital, alongside $100 million in debt.

Other rounds went to Function, a consumer health testing and personal health information company that raised $450 million from General Catalyst; Simile, an AI simulation startup that picked up more than $200 million at a $2 billion valuation just five months after launching its product; ThreatLocker, a cybersecurity provider with $190 million in Series F funding; CAIS, an alternative investment platform for independent financial advisors that raised $170 million at a valuation above $2 billion; PEX, whose AI-enabled business prepaid and charge card business raised $160 million in equity and debt; and Eliyan, an AI infrastructure connectivity company that completed its Series C at $145 million and a $1 billion valuation.

What the Megadeals Signal for AI Compute, Power and Private Valuations

Why Nvidia Is Aligning With Safe Superintelligence

The reported $5 billion deal is a clear example of Nvidia using its balance sheet to lock in demand for its chips. Frontier AI labs are among the largest buyers of Nvidia's highest-end GPUs, and an equity stake ties Safe Superintelligence's growth to Nvidia's roadmap. For the startup, the financing provides both capital and a compute partnership at a scale few rivals can match. The figure is reported rather than confirmed, and the exact terms of the partnership have not been disclosed.

The Energy Theme: Funding the Power Behind AI

Three of the top ten rounds — Commonwealth Fusion Systems, Antora Energy and Antares — are energy companies, not AI companies. That is a meaningful signal: data center operators face power constraints, and investors are positioning around electricity supply as the bottleneck. Commonwealth Fusion's $1 billion round, which brings its total funding to $4 billion, shows continued patience for fusion commercialization. Antora, which sells thermal batteries to data centers, is closer to revenue; Antares is targeting defense and space rather than the grid.

AI Infrastructure Companies Are Being Priced Quickly

Simile reached a $2 billion valuation in a round led by Greenoaks only five months after its product launch, and Eliyan crossed the $1 billion mark with a $145 million Series C led by Seligman Ventures. Both sit in the AI infrastructure layer — simulation and connectivity — rather than competing directly with foundation-model labs. That suggests investors are treating the entire AI stack as strategically valuable, not just the headline model-makers.

Health and Fintech Keep the Market Broad

Not every name on the list is AI infrastructure. Function, backed by General Catalyst, raised $450 million for consumer lab testing and health data; CAIS, led by Vista Equity Partners, raised $170 million at a valuation above $2 billion; and PEX raised $160 million for AI-enabled business payment cards. The breadth indicates that late-stage private capital is still available outside the AI theme, though the largest checks are clearly concentrated in AI and energy.

What VCs and Founders Should Watch in This Week's Megadeals

• For startup founders: Safe Superintelligence's reported Nvidia deal shows that compute access is becoming as valuable as cash in frontier AI; founders building compute-heavy products should consider strategic capital from infrastructure vendors, not just financial investors.
• For energy and infrastructure investors: the $1 billion Commonwealth Fusion round, $550 million Antora Series C and $370 million Antares raise point to lasting appetite for data center power solutions — but fusion and microreactor timelines remain long, so diligence should focus on near-term revenue paths such as Antora's thermal batteries.
• For later-stage VCs: Simile's $2 billion valuation five months after launch and Eliyan's $1 billion Series C signal aggressive pricing for AI infrastructure; founders should expect the next data points on revenue and customer traction to determine whether those marks hold.
• For market observers: the combined $8.2 billion across ten rounds shows strong private-market liquidity among U.S. startups, but the concentration of the largest check in one reported Nvidia transaction means the weekly total overstates the breadth of available mega-round capital.