Citadel Hedge Fund: How Ken Griffin Built a $65 Billion Firm

Citadel says it held about $65 billion of investment capital on 1 January 2026. Ken Griffin started the firm in 1990 with $4.6 million, according to Citadel's own history page.

This guide covers the firm's start and size, the strategies it runs, and where Citadel Securities, a separate market maker, fits. The facts come from filings with the US Securities and Exchange Commission (SEC), an SEC order, Citadel's own pages, and press reports, all opened on 4 November 2026.

Griffin began trading convertible bonds from his Harvard dormitory in 1987, according to Citadel's history page. A convertible bond is a bond that its holder can swap for shares.

The page says his success at Glenwood Partners, where he worked with Frank Meyer, led him to start his own fund in 1990. Wellington Financial Group began with $4.6 million. The fund took the name Citadel in 1994.

Source: Citadel history page, SEC order of 13 January 2017, press reports and company announcements named in the table

A multistrategy fund trades several strategies side by side. A multi-manager fund splits its money among many teams, each with its own portfolio. Our guide to the multi-manager hedge fund explains the pods, limits, and payouts.

Citadel calls its main funds multistrategy. Its history page dates later launches: credit and fixed income in 1999, equities in 2001, macro in 2008, and quantitative strategies in 2012.

Citadel Advisors LLC files the Form ADV. It names 37 private funds, including master funds for equities, fixed income, quantitative strategies, and tactical trading. A master fund is the main pool that other funds invest in.

The form says Citadel charges a percentage of assets, performance-based fees, and reimbursement of expenses. Our guide to hedge fund fees covers these charges.

Chart 1 shows six capital milestones from Citadel's history page.

The page labels them assets under management. It gives the 1 January 2026 figure as investment capital, combined across funds.

The Form ADV gives a much larger number. In an amendment filed on 11 June 2026, Citadel Advisors reports $570.6 billion of regulatory assets under management. The SEC's instructions say a firm must not deduct outstanding debt or other unpaid liabilities.

The returns below are press reports of flagship fund results.

Press reports name Kensington and Wellington as Citadel's two flagship funds. Citadel's history page says its 1990 fund, Wellington Financial Group, is now Citadel Wellington LLC.

A November 2009 CBS News MoneyWatch column says the main Kensington and Wellington funds lost 55% in 2008.

A December 2009 Reuters report by Svea Herbst-Bayliss, carried by International Business Times, says investors asked for about $1 billion back. Citadel temporarily suspended withdrawals in late 2008. It paid all of those requests by December 2009, people familiar with the matter told Reuters.

Citadel's page says it cleared its high-water mark in 2012. A high-water mark is the highest value of an investor's holding. A fund charges performance fees only on gains above it.

Fortune published a Bloomberg report on 23 January 2023. It put Citadel's 2022 profit for clients at a record $16 billion, based on estimates by LCH Investments, a fund of hedge funds.

Citadel Securities is a market maker, a firm that quotes a buying price and a selling price at the same time. Our guide to what a market maker does covers the business.

Citadel's history page says Citadel Securities was founded in 2002. It calls the two companies "two separate and distinct financial firms". The Form ADV lists Citadel Securities LLC, an SEC-registered dealer and futures commission merchant, as a related person. It answers yes to common control and no to either firm controlling the other.

In January 2022, Sequoia led a $1.15 billion minority investment that valued Citadel Securities at about $22 billion, according to the announcement by Citadel Securities.

A Form 13F is the quarterly report of US-listed holdings that managers with at least $100 million in covered securities file with the SEC. The latest filing at the time of writing covers 30 June 2026, as restated on 2 September 2026. Its information table lists one line for each holding, 16,122 lines worth $875.0 billion.

That total does not measure money invested. The SEC's instructions say to list options in terms of the shares underneath them. A call option gives the right to buy a share at a set price, while a put option gives the right to sell one. The information table counts calls and puts as positive values.

Chart 2 shows the reported value at 27 quarter-ends, from 31 December 2019 to 30 June 2026.

The value rose from $230.5 billion to $875.0 billion, which is the high of the window. It fell in 8 of the 26 quarter-on-quarter changes. The latest change was a rise of 41.5%, from $618.5 billion at 31 March 2026. The low was $222.5 billion, at 31 March 2020.

Chart 3 splits the latest quarter by type of line. Options hold 80.1% of the value. Shares hold 19.9%.

A filer may name other managers that share investment discretion over its holdings. This filing names one, Citadel Securities GP LLC. Most of its lines carry that name, so the 13F does not show the hedge funds alone.

On 13 January 2017, the SEC accepted a settlement with Citadel Securities. The order covers Citadel Execution Services, its wholesale market-making unit. A wholesale market maker handles retail orders that other firms send it. It often takes the other side of the trade itself.

The SEC found that statements to retail brokerage firms from late 2007 to January 2010 were misleading.

The statements suggested orders would get the best price Citadel Execution Services observed, but two of its algorithms did not do that. Citadel Securities paid a $16 million civil penalty, $5.2 million of disgorgement, and $1.5 million of interest. It neither admitted nor denied the findings.

An SEC staff report dated 14 October 2021 covers the GameStop trading of January 2021. It does not state the views of the Commission. The report says Citadel Securities accounted for nearly 50% of the dollar volume that internalizers executed in GameStop that month. Internalizers take the other side of retail orders.

On 27 January, Citadel Securities internalized nearly $4.2 billion of the stock, against a mean of just under $37 million a day in December 2020.

The report cites Griffin's written testimony of 18 February 2021 that Citadel had no role in Robinhood's decision to limit trading in GameStop.

Citadel's global headquarters is at 830 Brickell Plaza in Miami, the address on its SEC filings. Griffin announced the move from Chicago in a memo to staff on 23 June 2022, Fortune reported.

The 13F lists holdings but shows no fund-level returns. Our guide to whether hedge funds beat the market covers the evidence on returns. Our guide to what a hedge fund is sets out the structure.

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Citadel manages money for investors in hedge funds, while Citadel Securities is a market maker that trades with clients. Citadel's history page calls them two separate and distinct financial firms. Citadel's Form ADV lists them as under common control, with neither controlling the other.

Citadel states about $65 billion of investment capital as of 1 January 2026. Its Form ADV, filed on 11 June 2026, reports $570.6 billion of regulatory assets under management. That figure does not deduct debt or other liabilities, so the two numbers measure different things.

The Form ADV shows Ken Griffin, the chief executive, as a member of two entities above the adviser, each with the form's top ownership code, 75% or more. He is also co-chief investment officer. The form lists Citadel Securities LLC as a related person under common control.

Citadel's global headquarters is at 830 Brickell Plaza in Miami, the address on its SEC filings. Griffin announced the move from Chicago on 23 June 2022. Citadel's history page lists its first London office in 1999 and its first Asia-Pacific office, in Hong Kong, in 2005.

Citadel calls its main funds multistrategy, which means they run several strategies side by side. A multi-manager fund gives separate portfolios to many managers. Its history page dates the launch of credit, equities, macro, and quantitative strategies between 1999 and 2012. Our guide to the multi-manager hedge fund explains the model.

DISCLAIMER: This article is intended for educational purposes only. Any information or analysis in this note does not constitute an offer to sell or a solicitation of an offer to buy any securities. Nothing in this note is intended to be investment advice, nor should it be relied upon to make investment decisions. Any opinions, analyses, or probabilities expressed in this note are those of the author as of the note's date of publication and are subject to change without notice.