NBIS Stock Soars Over 10% — Ex-OpenAI Researcher’s Fund Reveals Massive Stake

• Situational Awareness disclosed ownership of 12.41 million Nebius shares, representing about 5% of the company.
• The position was reportedly valued at around $2.6 billion based on current market prices.
• In September 2025, Nebius and Microsoft signed a multi-billion dollar deal for AI infrastructure.

Shares of Nebius Group (NBIS) gained more than 10% on Thursday after a regulatory filing revealed a significant stake in the AI infrastructure company by Situational Awareness, a hedge fund managed by former OpenAI researcher Leopold Aschenbrenner.

The rally pushed Nebius shares to their highest level in two weeks.

Former OpenAI Researcher’s Fund Takes Stake In NBIS

According to a Schedule 13G filing with the Securities and Exchange Commission, Situational Awareness disclosed ownership of 12.41 million shares, representing a 5.6% passive stake in the company.

The position makes the fund the largest shareholder in Amsterdam-based Nebius, reported Reuters, adding that based on current market prices, the stake is worth around $2.6 billion.

Situational Awareness managed about $4 billion in investments as of the end of March, according to CNBC. The fund counts several well-known technology and investment figures among its backers, including Stripe founders Patrick and John Collison, as well as Daniel Gross and Nat Friedman, who have recently been linked to Meta’s AI efforts.

NBIS: A Key Player In AI Infrastructure

Nebius operates as a vertically integrated cloud provider focused on artificial intelligence and high-performance computing. The company designs and runs its own data centers and server infrastructure across Europe and the United States.

The company has also secured major commercial partnerships. In September 2025, Microsoft (MSFT) entered into a multiyear agreement with Nebius worth $17 billion in expected revenue to provide computing capacity, further strengthening the company's role in the AI ecosystem.

NBIS Stock: What Retail Sentiment Says

Stocktwits sentiment on NBIS improved to “bullish” on Thursday from “neutral” a day earlier. Message volume was “high,” rising more than 55% over the past seven days and nearly 240% in the last 30 days.

NBIS shares have soared 475% in the past 12 months.

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