Hedge Fund Led by Ex-OpenAI Researcher Ousts BlackRock as Nebius’ Top Shareholder

OpenAI insider's fund buys 5.6% stake in Nebius valued at $2.6B; AI cloud revenue surges 841%, but debt tops $9.4B. Stock up 420%.

A former OpenAI insider has seized the largest single stake in Nebius, unseating BlackRock and sending a clear signal about where institutional money sees the next frontier in artificial intelligence. Leopold Aschenbrenner’s Situational Awareness LP now holds 5.6% of the AI infrastructure company, a position valued at roughly $2.6 billion. The news propelled Nebius shares as much as 12% higher in pre-market trading on Thursday.

The hedge fund’s bold move landed just as Nebius unveiled quarterly numbers that defy easy comparison. Revenue hit $399 million in the first three months of 2026, a 684% leap from a year earlier. Almost all of that – 98% – came from the AI cloud division, where sales surged 841%. Adjusted EBITDA margins in that core segment hit 45%, more than double the prior quarter. Company-wide, the margin stood at 32.45%.

Behind the top-line explosion is a breakneck infrastructure buildout that has pushed total debt from $288 million in 2022 to over $9.4 billion. Nebius now has 3.5 gigawatts of power capacity under contract, eclipsing an original target of 3 GW for the end of 2026. Management has raised the bar to 4 GW. The annualized revenue run rate hit $1.92 billion, and the company expects to close fiscal 2026 with revenue between $7 billion and $9 billion. Street estimates are more conservative at $3.4 billion for this year, but jump to $10.9 billion for 2027.

The stock has climbed more than 420% over the past twelve months, though it has pulled back sharply from a recent high of $233.80 to $202 in just three sessions. The market capitalisation stands at $53 billion – a multiple that already prices in years of growth. The price-to-earnings ratio of 72.6 is more than double the sector median of 29.2. D.A. Davidson rates the shares neutral with a $250 price target.

Analysts point to two looming risks: capital intensity that will keep debt elevated, and the threat of hyperscalers like Amazon and Alphabet muscling into the same niche. Meanwhile, Nebius has signalled it may raise fresh equity through at-the-market offerings, a move that would dilute existing holders. On the other side of the ledger, the company’s backlog of signed contracts totals nearly $49 billion, and key customers – including Meta, which committed up to $27 billion, and Nvidia, which invested $2 billion – are already in line for upcoming capacity. The May acquisition of GPU specialist Eigen AI for $643 million only reinforces the thesis that Nebius is betting everything on speed. Whether that velocity can outrun the debt clock will define the story from here.