Leopold Aschenbrenner, the 23-year-old former OpenAI researcher who became one of the most watched figures in AI investing after building his Situational Awareness hedge fund from scratch in 2024, was forced to sell his entire public stock portfolio in a single block trade on Thursday, with Ken Griffin's Citadel as the buyer.
The fund that had grown to as much as $45 billion and posted gains of 439 percent through June 2026 has been shattered by July's AI selloff.
The losses came from two directions simultaneously. Long positions in AI infrastructure stocks, most notably SK Hynix, the South Korean memory chip maker whose US IPO coincided with a broader unwind of leveraged positions in Korean stocks, fell sharply.
Short positions in software companies including Adobe moved against the fund as software stocks rallied.
The combination, amplified by significant leverage supplied by prime brokers including Bank of America, Goldman Sachs and JPMorgan, triggered margin calls the fund could not meet without selling.
Aschenbrenner wrote in a July 24 investor letter that lower AI valuations had created the most attractive entry points he had seen since the fund's launch, but the capital to take advantage of them was gone.
The fund had also been trying to sell stakes in privately held companies including Anthropic, where his wife Avital Balwit serves as chief of staff to CEO Dario Amodei, to raise cash. Citadel's purchase of the public book is what CNBC confirmed Thursday morning.