Four banks, one blown-up AI fund, and a subpoena aimed at the lending desks

Take the disclosed figures at face value and the margin arithmetic is not hard to follow. RCK Analytics put the fund at close to four times leverage ^[9]. The end-June 13F showed SanDisk and Micron together at 55% of a $20.24 billion US stock portfolio ^[10], which is roughly $11.1 billion in two names ^[1]. At 4x gross, that book implies an equity base near $5.1 billion ^[2], so those two positions alone were carrying about 2.2 times capital ^[3]. The relevant shares then fell between 35% and 47% ^[11]. Applied to $11.1 billion, that is $3.9 billion to $5.2 billion of mark-to-market damage ^[4], or 77% to 103% of the implied equity ^[6]. A 67% July drawdown ^[2] is what that looks like once three brokers, Goldman and JPMorgan among them, stop waiting for the position to recover ^[11].

Hold those numbers loosely. The leverage estimate and the portfolio figure come from different bases, a third-party analytics report and a regulatory filing that only captures US long equity, and the same report dates the fund's 439% gain to a first half of 2026 ^[9] that does not sit comfortably with a July loss reported in August ^[1].

The disclosure gap is the part the filings cannot close. The Wall Street Journal reported on August 17 that Aschenbrenner ran as much as $100 billion at peak, much of it borrowed, and was trying to dump nearly all his pre-IPO Anthropic stake overnight while the banks tightened ^[16]. That peak is about 4.9 times the 13F portfolio ^[5]. Whatever sat in the difference was not visible to anyone reading quarterly equity disclosures.

Which is why the requests went to the lenders. The SEC wants the timing of the trades that set off the margin calls and the banks' communications with the fund about how much leverage it was carrying ^[3]. That is a question about what four prime brokers knew, when they knew it, and what they did about it, not about whether memory chips were a good idea. The exit tells the same story: unable to meet the calls, the fund sold its entire public equity book to Citadel ^[13], and Citadel, which runs around $77 billion, has since resold more than 80% of it through nearly 100 block trades worth over $4 billion ^[14][15]. The clearing mechanism for a blown-up AI concentration was a larger competitor's balance sheet.

On the underlying trade, Micron reported record third-quarter revenue of $41.46 billion with memory prices still rising ^[18]. Aschenbrenner told investors the fund "came closer to permanent capital impairment than is acceptable to us" ^[12]. Both things can be true, and that combination is what central banks have been warning about: leverage stacked on a narrow set of AI names as a financial-stability question ^[19], with the Bank of England among the regulators watching ^[20].

Reuters is explicit that an inquiry is not an enforcement action and that a records request does not make the banks targets ^[4]. The fund says scrutiny of high-profile funds with dramatic drawdowns is to be expected and that it will cooperate fully ^[5]. The SEC and all four banks declined to comment ^[6], and the underlying account traces to one person familiar with the matter, with the New York Times first reporting the subpoenas ^[7].