Aschenbrenner’s $11 Billion Bet on Chipmakers Preceded Hedge Fund Collapse

The scale of the shift was stark. In just three months, Aschenbrenner ramped up his holdings from less than $4 billion in direct stocks to a portfolio dominated by a $5.7 billion stake in SanDisk and a $5.6 billion position in Micron. This concentration reached 56% of his US equity holdings, a move paired with a drastic reduction in protective put options—down from 11 to just one. The firm also aggressively expanded its footprint in TSMC and initiated a $1.2 billion position in Nebius.

This aggressive pivot backfired when the AI sector faced a brutal July sell-off. SanDisk shares plummeted 47% and Micron fell 29%, triggering margin calls that forced Aschenbrenner to liquidate the bulk of his public holdings to Citadel, the firm managed by Ken Griffin. While 13F disclosures offer only a seasonal snapshot and exclude private investments like his stake in Anthropic, the filing confirms a departure from his previous hedging strategy. Aschenbrenner, a former OpenAI researcher who had claimed a 1,000% gain since his fund's inception, saw his highly leveraged portfolio drop 67% in value during the July volatility.