Shares of AI infrastructure firm Nabius Group rose more than 10% in premarket trading on Thursday after Situational Awareness, a fund run by a former OpenAI employee named Leopold Aschenbrenner, became its largest shareholder.

The gains put the stock on track to open at its highest level in two weeks. The fund held a 5.6% stake in Nebius, which was valued at about $2.6 billion as of Wednesday.

Situational awareness managed $13.67 billion as of March 31, representing 148% growth from the end of 2025. It is run by Aschenbrenner, who was previously part of the “superalignment” team at OpenAI.

The team, working to ensure that AI remains consistent with human values, has since been disbanded.

The Nabius bet represents a vote of confidence in the company as a key player in the AI ​​infrastructure race. Earlier this month, Nebius reported a nearly eight-fold increase in quarterly revenue.