Arcellx, Inc.
US ˙ NasdaqGS ˙ US03940C1009
DETTE SYMBOL ER IKKE LÆNGERE AKTIVT

SecurityACLX / Arcellx, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership21,806 shares
Latest Disclosed Value $ 2,503,765
Citadel Advisors Llc ownership in ACLX / Arcellx, Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 21,806 shares of Arcellx, Inc. (US:ACLX) valued at $2,503,765 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 1,500,223 shares of Arcellx, Inc.. This represents a change in shares of -98.55% during the quarter. The current value of the position is $2,509,216 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (ACLX) in the form of stock options. The firm currently holds call options representing 10,800 of underlying shares valued at $1,240,056 USD and put options representing 20,100 of underlying shares valued at $2,307,882 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

ACLX / Arcellx, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F ARCELLX COMMON STOCK 03940C100 21,806 -1,478,417 -98.55 2,504 -97.44 0.0004
2026-02-17 2025-12-31 13F ARCELLX COMMON STOCK 03940C100 1,500,223 478,770 46.87 97,815 16.64 0.0147
2025-11-14 2025-09-30 13F ARCELLX COMMON STOCK 03940C100 1,021,453 823,090 414.94 83,861 542.02 0.0128
2025-08-14 2025-06-30 13F ARCELLX COMMON STOCK 03940C100 198,363 -527,764 -72.68 13,062 -72.58 0.0023
2025-05-15 2025-03-31 13F ARCELLX COMMON STOCK 03940C100 726,127 700,901 2,778.49 47,634 2,362.93 0.0090
2025-02-14 2024-12-31 13F ARCELLX COMMON STOCK 03940C100 25,226 8,139 47.63 1,935 35.62 0.0003
2024-11-14 2024-09-30 13F ARCELLX COMMON STOCK 03940C100 17,087 17,087 1,427 0.0003
2024-08-14 2024-06-30 13F ARCELLX COMMON STOCK 03940C100 0 -77,730 -100.00 0 -100.00
2024-05-15 2024-03-31 13F ARCELLX COMMON STOCK 03940C100 77,730 54,534 235.10 5,406 320.05 0.0010
2024-02-14 2023-12-31 13F ARCELLX COMMON STOCK 03940C100 23,196 -21,500 -48.10 1,287 -19.71 0.0003
2023-11-14 2023-09-30 13F ARCELLX COMMON STOCK 03940C100 44,696 -316,379 -87.62 1,604 -85.96 0.0003
2023-08-14 2023-06-30 13F ARCELLX COMMON STOCK 03940C100 361,075 -1,153,821 -76.17 11,417 -75.54 0.0024
2023-05-15 2023-03-31 13F ARCELLX COMMON STOCK 03940C100 1,514,896 -180,910 -10.67 46,674 -11.16 0.0103
2023-02-14 2022-12-31 13F ARCELLX COMMON STOCK 03940C100 1,695,806 -50,164 -2.87 52,536 60.31 0.0123
2022-11-14 2022-09-30 13F ARCELLX COMMON STOCK 03940C100 1,745,970 -23,430 -1.32 32,772 4.59 0.0075
2022-08-15 2022-06-30 13F ARCELLX COMMON STOCK 03940C100 1,769,400 450,374 34.14 31,333 74.24 0.0080
2022-05-16 2022-03-31 13F ARCELLX COMMON STOCK 03940C100 1,319,026 1,319,026 17,983 0.0037
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F ARCELLX COMMON STOCK Call 10,800 107.69 1,240 265.78 n/a n/a n/a
2026-02-17 2025-12-31 13F ARCELLX COMMON STOCK Call 5,200 -68.48 339 -74.96 n/a n/a n/a
2025-11-14 2025-09-30 13F ARCELLX COMMON STOCK Call 16,500 9.27 1,355 36.22 n/a n/a n/a
2025-08-14 2025-06-30 13F ARCELLX COMMON STOCK Call 15,100 -71.18 994 -71.08 n/a n/a n/a
2025-05-15 2025-03-31 13F ARCELLX COMMON STOCK Call 52,400 53.22 3,437 31.08 n/a n/a n/a
2025-02-14 2024-12-31 13F ARCELLX COMMON STOCK Call 34,200 9.62 2,623 0.65 n/a n/a n/a
2024-11-14 2024-09-30 13F ARCELLX COMMON STOCK Call 31,200 49.28 2,606 125.93 n/a n/a n/a
2024-08-14 2024-06-30 13F ARCELLX COMMON STOCK Call 20,900 53.68 1,153 22.01 n/a n/a n/a
2024-05-15 2024-03-31 13F ARCELLX COMMON STOCK Call 13,600 -58.15 946 -47.59 n/a n/a n/a
2024-02-14 2023-12-31 13F ARCELLX COMMON STOCK Call 32,500 712.50 1,804 1,160.84 n/a n/a n/a
2023-11-14 2023-09-30 13F ARCELLX COMMON STOCK Call 4,000 -41.18 144 -33.49 n/a n/a n/a
2023-08-14 2023-06-30 13F ARCELLX COMMON STOCK Call 6,800 65.85 215 70.63 n/a n/a n/a
2023-05-15 2023-03-31 13F ARCELLX COMMON STOCK Call 4,100 -83.27 126 -83.40 n/a n/a n/a
2023-02-14 2022-12-31 13F ARCELLX COMMON STOCK Call 24,500 26.29 759 108.52 n/a n/a n/a
2022-11-14 2022-09-30 13F ARCELLX COMMON STOCK Call 19,400 364 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F ARCELLX COMMON STOCK Put 20,100 -33.44 2,308 17.17 n/a n/a n/a
2026-02-17 2025-12-31 13F ARCELLX COMMON STOCK Put 30,200 65.03 1,969 31.09 n/a n/a n/a
2025-11-14 2025-09-30 13F ARCELLX COMMON STOCK Put 18,300 -81.86 1,502 -77.39 n/a n/a n/a
2025-08-14 2025-06-30 13F ARCELLX COMMON STOCK Put 100,900 842.99 6,644 847.79 n/a n/a n/a
2025-05-15 2025-03-31 13F ARCELLX COMMON STOCK Put 10,700 -71.77 702 -75.88 n/a n/a n/a
2025-02-14 2024-12-31 13F ARCELLX COMMON STOCK Put 37,900 -1.81 2,907 -9.84 n/a n/a n/a
2024-11-14 2024-09-30 13F ARCELLX COMMON STOCK Put 38,600 1,738.10 3,223 2,702.61 n/a n/a n/a
2024-08-14 2024-06-30 13F ARCELLX COMMON STOCK Put 2,100 -93.23 116 -94.67 n/a n/a n/a
2024-05-15 2024-03-31 13F ARCELLX COMMON STOCK Put 31,000 349.28 2,156 464.40 n/a n/a n/a
2024-02-14 2023-12-31 13F ARCELLX COMMON STOCK Put 6,900 30.19 383 101.05 n/a n/a n/a
2023-11-14 2023-09-30 13F ARCELLX COMMON STOCK Put 5,300 35.90 190 54.47 n/a n/a n/a
2023-08-14 2023-06-30 13F ARCELLX COMMON STOCK Put 3,900 -70.23 123 -69.48 n/a n/a n/a
2023-05-15 2023-03-31 13F ARCELLX COMMON STOCK Put 13,100 27.18 404 26.33 n/a n/a n/a
2023-02-14 2022-12-31 13F ARCELLX COMMON STOCK Put 10,300 319 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.