Jane Street lost about $15 billion in July, marking its first negative trading month since 2016, as a selloff in AI-related equities and other technology shares hit its investment in Situational Awareness and a broader set of Asian equity bets. A newly released second-quarter 13F filing shows the AI-focused hedge fund founded by former OpenAI researcher Leopold Aschenbrenner was heavily concentrated in SanDisk and Micron Technology as of June 30, 2026, with those two positions accounting for more than $11 billion in long exposure before the trade unraveled. CNBC's Leslie Picker said Aschenbrenner had sharply increased the stakes in both companies during the quarter and later sold much of the fund's liquid positions to Citadel after steep declines in July. SanDisk fell 55.32% between June 30 and July 29, while Micron dropped 35.97%, far worse than the SPDR S&P 500 ETF's 2.32% decline over the same period. Other public holdings including Bloom Energy, Taiwan Semiconductor Manufacturing and NIO also fell, while the VIX briefly reached 20.66 on July 29. Situational Awareness, which had managed $45 billion at its peak, saw assets fall to about $10 billion after the selloff, leaving its private holdings, including an estimated $5 billion Anthropic stake, as a key source of remaining support. Jane Street had invested roughly $2.5 billion in the fund, while partner Turner Batty said in an internal memo that the firm's core short-horizon market-making strategies remained profitable despite the broader July setback.