Via citadel.com
Ken Griffin's hedge fund grew its 13F portfolio 41.5% to $875.1 billion while making high-profile bets on space, AI hardware, and quantum computing
Citadel Advisors just handed the market a glimpse of where one of the world’s most powerful hedge funds is placing its chips. The firm’s Q2 2026 13F filing reveals new positions in SpaceX, Cerebras Systems, and Quantinuum, three companies operating at the intersection of aerospace, advanced AI hardware, and quantum computing.
The bigger headline buried inside that filing: Citadel’s equity portfolio ballooned to $875.1 billion, up 41.5% from the $618.5 billion it reported in Q1 2026. That’s $256 billion in new equity exposure added in a single quarter.
Three bets, three frontier sectors #
Cerebras Systems raised $1 billion in a Series H funding round led by Tiger Global in February 2026, a round that pegged its post-money valuation at roughly $23 billion. By June 2026, Cerebras had gone public on the Nasdaq under the ticker CBRS, raising $6.4 billion in what became one of the more closely watched tech IPOs of the year.
Citadel’s Q2 filing captures positions as of the end of the quarter, meaning its Cerebras stake likely reflects shares acquired either before or around the IPO window. The exact entry price and position size have not been disclosed in the filing.
Quantinuum reached a pre-money valuation of $10 billion in 2025 after raising roughly $600 million in equity.
None of the three new positions come with specific share counts or dollar values attached, which is typical for 13F filings involving private securities.
Why a 41.5% portfolio jump matters #
Citadel’s Q1 2026 filing listed more than 12,800 individual holdings, with Nvidia, Tesla, and Apple anchoring the top of the book.
Citadel operates across market-neutral and multi-strategy frameworks where hedging and cross-asset positioning can cause reported equity values to swing significantly quarter to quarter, depending on how options and derivatives exposure flows through the 13F calculation. A large jump in reported 13F value does not necessarily mean Citadel wrote $256 billion worth of new checks. It means the reportable long equity footprint expanded substantially.
What the new positions signal for these companies #
For Cerebras, the Citadel disclosure arrives after its IPO, which means the fund’s position is now sitting in a publicly traded stock. Cerebras competes in the AI accelerator market against Nvidia, a company Citadel already held as one of its top positions. The filing does not offer a timeline or price target for any of the three positions. No expert commentary or market analysis was available regarding the new stakes as of mid-August 2026.
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