Jane Street, one of the most powerful trading firms on Wall Street, suffered an extraordinary $15 billion hit in July after an AI-stock selloff battered positions connected to one of the market’s most aggressive artificial-intelligence investment funds.

Yet the loss reveals something equally remarkable: Jane Street has still generated more than $40 billion in trading revenue this year, already surpassing the $39.6 billion it produced during all of 2025.

The July setback was tied partly to Jane Street’s investment in Situational Awareness, an AI-focused hedge fund run by former OpenAI researcher Leopold Aschenbrenner.

The fund had grown rapidly as AI-related stocks surged during the first half of the year. But when semiconductor, memory and other AI-linked shares suddenly reversed in July, leveraged positions came under severe pressure.

Situational Awareness ultimately unloaded much of its stock portfolio in a distressed sale to Citadel after losses triggered margin calls.

Jane Street was caught in that reversal both through its investment in the fund and through other technology positions of its own.

Several major memory and semiconductor stocks fell roughly 50% during the July rout, according to a Jane Street communication to employees.

The result was Jane Street’s first negative month of trading revenue since 2016.

For perspective, a $15 billion loss would be catastrophic for almost any investment firm in the world.

For Jane Street, it interrupted an otherwise extraordinary year.

The privately held trading company has approximately 3,500 employees and operates across more than 200 trading venues worldwide, buying and selling stocks, bonds, ETFs, options, currencies and commodities.

Its scale allows the firm to hold enormous positions while providing liquidity to global markets.

That model can be extraordinarily profitable when markets move as expected.

July demonstrated what happens when they do not.

Jane Street said it has since reduced risk in some strategies and closed significant portions of positions associated with the losses.

The episode also offers investors a rare glimpse into how concentrated the AI trade has become.

Artificial intelligence is no longer simply a collection of popular technology stocks held by retail investors. Hedge funds, proprietary trading firms, banks and institutional investors have committed enormous amounts of capital to many of the same semiconductor, data-center, cloud-computing and memory companies.

That concentration can amplify gains when AI stocks rise.

It can also accelerate losses when investors attempt to exit similar positions simultaneously.

The most unusual part of Jane Street’s July loss may therefore be what happened afterward.

Despite absorbing approximately $15 billion in a single month, the firm remains on pace for what could still be the most profitable year in its history.

That says as much about the extraordinary amount of money being made around today’s markets as the loss itself.

But July delivered a warning that applies far beyond Jane Street:

A trade can become enormously profitable without becoming less dangerous.

And when billions of dollars are crowded into the same AI bets, a relatively short market reversal can produce losses measured not in millions — but in tens of billions.

JBizNews Desk | New York

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