ASP Isotopes Inc.
US ˙ NasdaqCM ˙ US00218A1051

SecurityASPI / ASP Isotopes Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership768,006 shares
Latest Disclosed Value $ 3,394,586
Citadel Advisors Llc ownership in ASPI / ASP Isotopes Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 768,006 shares of ASP Isotopes Inc. (US:ASPI) valued at $3,394,587 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 1,725,553 shares of ASP Isotopes Inc.. This represents a change in shares of -55.49% during the quarter. The current value of the position is $5,798,445 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (ASPI) in the form of stock options. The firm currently holds call options representing 1,159,500 of underlying shares valued at $5,124,990 USD and put options representing 714,500 of underlying shares valued at $3,158,090 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.

ASPI / ASP Isotopes 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 ASP ISOTOPES COM 00218A105 768,006 -957,547 -55.49 3,395 -63.23 0.0005
2026-02-17 2025-12-31 13F ASP ISOTOPES COM 00218A105 1,725,553 559,788 48.02 9,232 -17.68 0.0014
2025-11-14 2025-09-30 13F ASP ISOTOPES COM 00218A105 1,165,765 1,020,562 702.85 11,215 950.00 0.0017
2025-08-14 2025-06-30 13F ASP ISOTOPES COM 00218A105 145,203 145,203 1,069 0.0002
2024-08-14 2024-06-30 13F ASP ISOTOPES COM 00218A105 0 -50,695 -100.00 0 -100.00
2024-05-15 2024-03-31 13F ASP ISOTOPES COM 00218A105 50,695 -53,844 -51.51 209 11.76 0.0000
2024-02-14 2023-12-31 13F ASP ISOTOPES COM 00218A105 104,539 104,539 187 0.0000
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 ASP ISOTOPES COM Call 1,159,500 -47.70 5,125 -56.80 n/a n/a n/a
2026-02-17 2025-12-31 13F ASP ISOTOPES COM Call 2,216,900 66.18 11,860 -7.58 n/a n/a n/a
2025-11-14 2025-09-30 13F ASP ISOTOPES COM Call 1,334,000 1,120.49 12,833 1,496.14 n/a n/a n/a
2025-08-14 2025-06-30 13F ASP ISOTOPES COM Call 109,300 -68.54 804 -50.64 n/a n/a n/a
2025-05-15 2025-03-31 13F ASP ISOTOPES COM Call 347,400 235.65 1,629 248.08 n/a n/a n/a
2025-02-14 2024-12-31 13F ASP ISOTOPES COM Call 103,500 469 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 ASP ISOTOPES COM Put 714,500 12.96 3,158 -6.65 n/a n/a n/a
2026-02-17 2025-12-31 13F ASP ISOTOPES COM Put 632,500 23.58 3,384 -31.28 n/a n/a n/a
2025-11-14 2025-09-30 13F ASP ISOTOPES COM Put 511,800 9.24 4,924 42.78 n/a n/a n/a
2025-08-14 2025-06-30 13F ASP ISOTOPES COM Put 468,500 144.90 3,448 284.39 n/a n/a n/a
2025-05-15 2025-03-31 13F ASP ISOTOPES COM Put 191,300 43.51 897 48.76 n/a n/a n/a
2025-02-14 2024-12-31 13F ASP ISOTOPES COM Put 133,300 604 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.