- Jane Street suffered a $15 billion loss in July — its first monthly downturn in a decade and a figure that rivals the most infamous drops in hedge fund history (Morgan Stanley’s $7B subprime loss in 2007, the London Whale’s $6.2B in 2012) — driven by AI stock declines, Asian equity market bets, and its investment in Leopold Aschenbrenner’s Situational Awareness AI hedge fund.
- The loss lays bare a fundamental evolution in Jane Street’s strategy: the firm has been quietly adding longer-term directional bets — including stakes in private companies like Anthropic — that go well beyond traditional market-making and increasingly resemble the positioning of a hedge fund, a shift the firm acknowledged in its latest debt offering documents.
- Despite the staggering loss — equivalent to burning roughly $650 million per trading day in July — Jane Street has already generated more than $40 billion in net trading revenue year-to-date, surpassing its full-year 2025 record of $39.6 billion; partner Turner Batty acknowledged the loss but said the firm has cut risk and positions “seem appropriate for our present risk tolerance.”
- The episode raises pointed questions about the regulatory and systemic implications of a firm that describes itself as a market-maker taking on hedge fund-scale directional risk, at a moment when banks — prohibited from proprietary trading since the financial crisis — watch their less-regulated rivals operate with a significantly wider risk mandate.
What Happened?
Jane Street — the trading firm that last year generated $39.6 billion in trading revenue, surpassing JPMorgan’s entire fixed-income and equity trading operation — suffered a $15 billion loss in July, its first monthly decline in a decade. The hit came from multiple directions: AI stocks tumbled, Asian equity market bets went against the firm, and its investment in Situational Awareness — the AI hedge fund run by ex-OpenAI researcher Leopold Aschenbrenner — plunged as AI shares fell, forcing Aschenbrenner to offload most of his fund’s public equities book to meet margin calls. The July losses left Jane Street’s Situational Awareness stake flat on the year. Even with the massive monthly setback, Jane Street’s year-to-date revenue of more than $40 billion already surpasses its 2025 full-year total — underscoring just how extraordinary its good months have been.
Why It Matters?
Jane Street has long described itself as a market-maker and liquidity provider — a characterization that has helped it avoid the proprietary-trading restrictions imposed on banks after the 2008 financial crisis. But the $15 billion July loss exposes the fiction: you cannot lose $650 million per trading day through market-making alone. The firm has been building longer-term directional books — stakes in private AI companies, concentrated sector bets, longer time-horizon strategies that look far more like hedge fund positioning than bid-ask spread arbitrage. This evolution, now acknowledged in Jane Street’s own debt offering documents, creates systemic risk that regulators have not yet grappled with. If Citadel Securities is the model of a pure market-maker, Jane Street has become something else — and the July loss proves that “something else” carries risks previously associated only with levered hedge funds and pre-crisis bank prop desks.
What’s Next?
Jane Street has cut risk following the July losses, and partner Batty’s note to staff suggests the firm is actively managing down the concentrated positions that created the July exposure. But the strategic question — whether to continue building the directional book that produced both its record revenues and its worst monthly loss — is not resolved by cutting risk temporarily. Regulators, particularly the SEC and CFTC, are likely to scrutinize more carefully whether firms like Jane Street warrant different treatment than traditional market-makers. For competitors including Citadel Securities — which has deliberately maintained a purer market-making model — the episode may validate their more conservative approach. And for investors in private AI companies like Anthropic, the revelation that Jane Street held a significant stake adds another dimension to the secondary market dynamics that will shape pre-IPO pricing.
Source: Bloomberg
