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On July 24, Leopold Aschenbrenner wrote to his investors that the sell-off tearing through AI stocks had opened one of the best buying windows since early 2025. The Financial Times, which saw the letter, reported that he invited clients to commit fresh capital.
Six days later his prime brokers sold his entire public equity book to Citadel.
I feel that this wasn’t a failure of analysis or stock selection. Aschenbrenner's read on where AI money would flow beat Wall Street's, and the returns say so. What failed was the structure he used to hold the position. Those are different problems, and confusing them is how the next person repeats it.
Situational Awareness launched in July 2024, named after the 165-page essay that made its 22-year-old author briefly famous in Silicon Valley. CNBC reports it started with roughly $225 million from the Stripe founders Patrick and John Collison, Nat Friedman and Daniel Gross. Jane Street later came in as an investor, which is notable mostly because Jane Street rarely backs outside managers.
The thesis was simple enough to fit in a sentence: if AI models keep scaling, someone has to build the chips, the memory, the data centers and the power stations, and those builders are mispriced. So he bought memory producers, bitcoin miners converting to DC's, fuel cells, power infrastructure - and went short on the software companies he expected AI to devour.
It worked to a degree that is hard to state without sounding like promotion. The FT put the fund's first-half 2026 return at 439% net. The Wall Street Journal reported gains above 1,000% since inception. CNBC reports assets reached about $45 billion at the start of July.
Worth flagging: Outlets have variously described the firm at $45 billion, $24 billion and $20 billion in the same week, because "assets" for a levered fund can mean the equity investors put in or the gross value of everything the fund controls. I'll come back to why that distinction is the most important number in the story.
The Q1 2026 filings and subsequent disclosures show a portfolio of concentration: Nebius, SanDisk, Micron, CoreWeave, Bloom Energy, IREN, Core Scientific, Applied Digital, and outside the US filings a large SK Hynix position in Korea. In May the fund disclosed 12.4 million Nebius shares, a 5.6% stake, making it one of that company's largest outside holders. Against those longs sat short positions in software names including Adobe, plus put positions on the semiconductor ETF and Nvidia.
Reporting from the WSJ and CNBC puts the leverage at up to 400%.
Simply: for every dollar of investor money, the fund controlled roughly four dollars of stock, the other three borrowed from its brokers. That works beautifully in one direction. Run the arithmetic in the other and it is brutal - at four times gross, the book only has to fall about 25% before the investors' entire dollar is gone. Nebius, SanDisk, Micron and CoreWeave each fell more than 35% in July. SK Hynix fell roughly 47% from its June peak. The Philadelphia Semiconductor Index dropped more than 20% and entered a bear market, and Korea's Kospi lost roughly a third.
What turned a down month into a liquidation was the short book was supposed to be the hedge. Two directional bets on one idea. When AI infrastructure sold off, software was meant to fall with it, or at least not rally, and the profit on the shorts was meant to cushion the loss on the longs. In a letter reported by media outlets, Aschenbrenner advised LPs "we disappointed you this month," disclosing a 67% single-month loss, blaming short sellers targeting the fund's positions, likening it to a bank run, and confirming all leverage was removed,
Instead, as CNBC reported, software stocks like Adobe rallied while the AI complex collapsed. Both legs lost money at the same time. A hedged book stopped being hedged at the exact moment it was needed, which is the only moment a hedge is ever tested. From this the sequence is mechanical and has been the same since the early 1900's investment playbook. The equity cushion shrinks, the brokers - Bank of America, Goldman Sachs and JPMorgan Chase demand more collateral, or they close your position. The fund either finds cash or sells. Aschenbrenner tried to find cash. Bloomberg reports the August 1 appeal did not raise what he hoped. On July 30 the brokers marketed the book and Citadel bought it, below market. Assets fell to around $10 billion.
The firm survives. Reliant on liquidity, Situation Awareness will potentially keep its the largest of which the FT valued at roughly $5 billion in Anthropic, and continues as a private investment vehicle. The WSJ reports the remaining positions carry no borrowing.
Nothing about Nebius's contracted revenue changed because its largest outside shareholder got a margin call. When a holder of 5.6% of a company is liquidated into a falling market, the price that results tells you about that holder's balance sheet, not the business. Citadel, which is not a charity and which bought the whole package at a discount, evidently reached the same conclusion. And the underlying claim that AI requires an enormous physical build-out has not been disproven by three weeks of price action. It may well be the correct call of the decade, with cadences quickening and these large capex numbers become the norm.
The problem is that July delivered real information alongside the forced selling. The complex fell because public investors began asking, out loud, whether extraordinary capital expenditure was converting into near-term revenue.
Has anything like this happened before? Three comparisons, and only one of them fits, Archegos.
Archegos, 2021. The closest match by a distance. Bill Hwang lost around $20 billion of his own capital in two days when concentrated, swap-financed positions turned against him, and left banks with more than $10 billion in losses - Credit Suisse alone took $5.5 billion. Same mechanism, same speed, same ending, with brokers dumping a book they could not otherwise exit.
Amaranth, 2006. A $9 billion fund that lost roughly 65% of its assets, about $6.6 billion, on natural gas in weeks - and then sold its energy book to JPMorgan and Citadel. Citadel has played this role before.
LTCM, 1998. Cited constantly and the worst fit. LTCM lost $4.6 billion, less than the headline numbers here, but ran leverage above 25 to 1 and sat at the center of every major dealer's balance sheet, which is why the Federal Reserve convened a rescue. Its danger was systemic. This does not currently look systemic.
A key distinction. The fall from $45 billion to $10 billion is not $35 billion of investor money destroyed. Most of that figure was borrowed, and borrowed money that disappears takes the lender's exposure with it, not the investor's. No bank has disclosed a capital hole. One buyer absorbed the entire book in a single trade. Compared with Archegos, where nine lenders ate ten billion dollars between them, this has so far been contained - and the containment is the more interesting part.
The book on Long Term Capital Management - When Genius Failed: The Rise and Fall of Long-Term Capital Management. Book by Roger Lowenstein. Is legendary. If you have not read it, and love these sorts of stories, it will inspire you.
Here is the tension where the jury is still out. Aschenbrenner told investors this was the best entry point in eighteen months, then was liquidated six days later. Either he believed it, in which case he is a man whose conviction outran his financing - or the letter was partly an attempt to stop a run he could already see coming. The facts are settled; more will unravel in the media during the week.
A long-term investment thesis that needs four times leverage to be worth holding is not a thesis, it is a trade. If the AI build-out is the decade's great reallocation of capital, it will pay unlevered investors handsomely over years and require no borrowed money whatsoever. Aschenbrenner's error was not being early or wrong. It was building a position that had to be right continuously, when he only needed to be right eventually.
If you hold any of these names, the thing to understand is that your position was recently priced by someone else's margin call.
If you use margin yourself, take the one transferable lesson: leverage does not change what you own, it changes how long you are allowed to own it. Every forced seller in history was solvent on a long enough timeline.
And if you are tempted to conclude that the AI trade is over - the end of the AI trade won't be signaled by a levered fund blowing up; it'll be signaled by hyperscaler capex guidance rolling over. Queues from the Magnificent 7 providing quarterly market updates which show capex spend is trending downwards or they overtly state that they are either gently applying the brakes or pulling the handbrake.