[SCHEDULE 13G/A] ASP Isotopes Inc. SEC Filing

Rhea-AI Filing Summary

AWM Investment Company, Inc. reports beneficial ownership of 3,931,186 shares of ASP Isotopes Inc., representing 4.3% of the outstanding common stock. AWM states it is the investment adviser to five funds and holds sole voting and sole dispositive power over the shares allocated across those funds, with individual fund holdings disclosed in the filing. The disclosure identifies the funds by name and provides a per‑fund share breakdown, making the ownership position transparent.

Filing statements indicate the shares are held in the ordinary course of business and were not acquired to change or influence control of the issuer. The filing also names the controlling principals associated with the funds and confirms there is no shared voting or dispositive power reported.

Positive

• Clear disclosure of beneficial ownership totaling 3,931,186 shares (4.3%), improving investor transparency
• Sole voting and dispositive power reported for the holdings, with a detailed per-fund breakdown across five funds

Negative

• None.

Insights

Financial Analyst

TL;DR: AWM holds a disclosed, non-controlling 4.3% stake across five funds with sole voting/dispositive power; impact appears limited and routine.

The filing shows AWM as adviser to five funds that together own 3,931,186 shares (4.3%) of ASP Isotopes, with sole voting and dispositive power and no shared control. Because the stake is below 5% and the filer certifies holdings are in the ordinary course and not intended to change control, this disclosure increases transparency but does not, by itself, signal a material control shift or immediate market-moving event.

Corporate Governance Expert

TL;DR: Ownership is clearly allocated across funds and controlled by AWM, with named principals linked to general partners; governance implications appear limited.

The statement identifies AWM as holding sole voting and investment power for shares held by five named funds and notes that Greenhouse and Stettner are controlling principals tied to the funds' general partners. There is no reported shared voting/dispositive power and no group filing. From a governance standpoint, this is a standard disclosure of adviser-controlled fund holdings rather than an actionable governance challenge.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

ASP Isotopes Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

00218A105

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 00218A105

1

Names of Reporting Persons

AWM Investment Company, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 3,931,186.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 3,931,186.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,931,186.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.3 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: *AWM Investment Company, Inc., a Delaware corporation (AWM), is the investment adviser to Special Situations Cayman Fund, L.P. (CAYMAN), Special Situations Fund III QP, L.P. (SSFQP), Special Situations Private Equity Fund, L.P. (SSPE), Special Situations Technology Fund, L.P. (TECH) and Special Situations Technology Fund II, L.P. (TECH II) (CAYMAN, SSFQP, SSPE, TECH and TECH II will hereafter be referred to as the Funds). As the investment adviser to the Funds, AWM holds sole voting and investment power over 504,061 shares of Common Stock of the Issuer (the Shares) held by CAYMAN, 1,798,402 Shares held by SSFQP, 286,468 Shares held by

SCHEDULE 13G

Item 1.
(a)	Name of issuer: ASP Isotopes Inc.
(b)	Address of issuer's principal executive offices: 601 PENNSYLVANIA AVENUE NW, 601 PENNSYLVANIA AVENUE NW, WASHINGTON, DISTRICT OF COLUMBIA, 20004.
Item 2.
(a)	Name of person filing: AWM Investment Company, Inc., a Delaware corporation (AWM), is the investment adviser to Special Situations Cayman Fund, L.P. (CAYMAN), Special Situations Fund III QP, L.P. (SSFQP), Special Situations Private Equity Fund, L.P. (SSPE), Special Situations Technology Fund, L.P. (TECH) and Special Situations Technology Fund II, L.P. (TECH II). As the investment adviser to the Funds, AWM holds sole voting and investment power over 504,061 shares of Common Stock of the Issuer (the Shares) held by CAYMAN, 1,798,402 Shares held by SSFQP, 286,468 Shares held by SSPE, 224,765 Shares held by TECH and 1,117,490 Shares held by TECH II
(b)	Address or principal business office or, if none, residence: The principal business address for AWM is c/o Special Situations Funds, 527 Madison Avenue, Suite 2600, New York, NY 10022.
(c)	Citizenship: AWM is a Delaware Corporation
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 00218A105
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 3,931,186
(b)	Percent of class: 4.3 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: AWM is the investment adviser to each of the Funds. As the investment adviser to the Funds, AWM holds sole voting power over 504,061 shares of Common Stock of the Issuer (the Shares) held by CAYMAN, 1,798,402 Shares held by SSFQP, 286,468 Shares held by SSPE, 224,765 Shares held by TECH and 1,117,490 Shares held by TECH II. Greenhouse and Stettner are members of SSCAY, the general partner of CAYMAN. Greenhouse and Stettner are members of: MGP, the general partner of SSFQP; MG, the general partner of SSPE and SSTA, the general partner of TECH and TECH II. Greenhouse and Stettner are also controlling principals of AWM
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: AWM is the investment adviser to each of the Funds. As the investment adviser to the Funds, AWM holds sole investment power over 504,061 shares of Common Stock of the Issuer (the Shares) held by CAYMAN, 1,798,402 Shares held by SSFQP, 286,468 Shares held by SSPE, 224,765 Shares held by TECH and 1,117,490 Shares held by TECH II. Greenhouse and Stettner are members of SSCAY, the general partner of CAYMAN. Greenhouse and Stettner are members of: MGP, the general partner of SSFQP; MG, the general partner of SSPE and SSTA, the general partner of TECH and TECH II. Greenhouse and Stettner are also controlling principals of AWM
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

AWM Investment Company, Inc.

Signature:	Adam Stettner
Name/Title:	Executive Vice President
Date:	08/14/2025

FAQ

How many ASP Isotopes (ASPI) shares does AWM beneficially own?

AWM reports beneficial ownership of 3,931,186 shares of ASP Isotopes common stock.

What percentage of ASPI does AWM's stake represent?

The reported holdings represent 4.3% of the class.

Does AWM have voting control over the reported shares?

Yes. AWM states it holds sole voting and sole dispositive power over the shares held by the five funds.

Are the shares held to influence control of ASP Isotopes?

The filing certifies the shares were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of the issuer.

Which funds hold the shares reported by AWM?

The filing lists five funds: Special Situations Cayman Fund, L.P.; Special Situations Fund III QP, L.P.; Special Situations Private Equity Fund, L.P.; Special Situations Technology Fund, L.P.; and Special Situations Technology Fund II, L.P. with per-fund share counts provided in the filing.