Jane Street reports first monthly loss in a decade, bleeding $15 billion in July

Jane Street, the quantitative trading powerhouse that has spent the better part of a decade looking almost supernaturally profitable, finally had a bad month. A really bad month. The firm lost approximately $15 billion in July 2026, marking its first negative month since 2016 and the largest single-month loss in the company’s history. Revenue dropped roughly 25% from June, a stunning reversal for a firm whose trading desks have essentially printed money for years. What went wrong The short answer: AI exposure, and lots of it. Jane Street’s losses were driven in large part by its stake in Situational Awareness, the AI-focused hedge fund founded by former OpenAI researcher Leopold Aschenbrenner. The fund’s value had climbed near $10 billion before dropping sharply, dragging Jane Street’s books down with it. AI-exposed equities, particularly in the semiconductor sector, experienced declines of approximately 50% during July. When you’re a firm that has placed big, concentrated bets across the AI ecosystem, a month like that doesn’t just sting. It leaves a crater. The losses reflect Jane Street’s strategic pivot in recent years toward longer-term investment positions, a departure from t...