UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 27, 2025

ASP Isotopes Inc.

(Exact name of registrant as specified in its charter)

Delaware

001-41555

87-2618235

(State or other jurisdiction of

incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

601 Pennsylvania Avenue NW

South Building, Suite 900

Washington, DC

20004

(Address of principal executive offices)

(Zip Code)

Registrant’s telephone number, including area code: (202) 756-2245

Not Applicable

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading symbol(s)		Name of each exchange on which registered
Common Stock, par value $0.01		ASPI		The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act ☐

Item 1.01. Entry into a Material Definitive Agreement.

On November 27, 2025, ASP Isotopes Inc. (the “Company” or “ASP Isotopes”) and Renergen Limited (“Renergen”), a South African company listed on the exchange operated by the JSE Limited and the Australian Securities Exchange, entered into a letter agreement to extend the date for the fulfillment of the conditions to the previously announced offer by the Company to acquire 100% of the ordinary shares (excluding treasury shares) of Renergen, pursuant to a scheme of arrangement under South African law pursuant to which Renergen shareholders will receive 0.09196 new ASP Isotopes shares for each Renergen share held on the record date (the “Scheme”).

The longstop date, which was originally set at September 30, 2025 and extended by ASP Isotopes to November 28, 2025, has been further extended by mutual agreement to January 30, 2026 in order to allow the parties additional time to satisfy conditions to closing relating to the receipt of the remaining required regulatory approval and certain third party consents. As of November 27, 2025, the implementation of the Scheme remained subject to the approval of the Financial Surveillance Department of the South African Reserve Bank (FinSurv) as provided for in the South African Exchange Control Regulations (in terms of the South African Currency and Exchanges Act, 1933). ASP Isotopes and Renergen continue to pursue a timely approval of the Scheme with FinSurv and certain third parties in order to implement the Scheme as promptly as possible. To date, the Scheme has been approved by the Competition Commission of South Africa, subject to certain conditions, which are acceptable to the Company, and third-party consents have been received from the Industrial Development Corporation of South Africa and the U.S. International Development Finance Corporation.

In addition, on November 27, 2025, the Company, ASP Isotopes South Africa Proprietary Limited (“ASPI South Africa”) and Renergen entered into an amendment to the Term Loan Facility Agreement, dated May 19, 2025, by and among the Company, ASP Isotopes South Africa, as lender, and Renergen, as borrower, to extend the final repayment date thereunder to January 30, 2026.

The foregoing descriptions of the letter agreement to extend the date for the fulfillment of the conditions and the amendment to the Term Loan Facility Agreement are qualified in their entirety by reference to the full text of such documents, copies of which are filed as Exhibits 2.1 and 10.1 to this Current Report on Form 8-K and are incorporated in this Item 1.01 by reference.

Forward-Looking Statements

This Current Report on Form 8-K contains “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by words like “may,” “will,” “likely,” “should,” “expect,” “anticipate,” “future,” “plan,” “believe,” “intend,” “goal,” “seek,” “estimate,” “project,” “continue,” and variations of such words and similar expressions. These forward-looking statements are not guarantees of future performance and involve risks, assumptions, and uncertainties, including, but not limited to, risks related to: (i) the implementation of the Scheme in the anticipated timeframe or at all; (ii) the satisfaction of the Scheme conditions; (iii) the failure to obtain necessary regulatory approvals; (iv) the ability to realize the anticipated benefits of the proposed acquisition of Renergen; (v) the ability to successfully integrate the businesses; (vi) disruption from the proposed acquisition of Renergen making it more difficult to maintain business and operational relationships; (vii) the negative effects of this announcement or the consummation of the proposed acquisition of Renergen on the market price of Renergen’s or ASPI’s securities; (viii) significant transaction costs and unknown liabilities; (ix) litigation or regulatory actions related to the proposed acquisition of Renergen; and (x) such other factors as are set forth in the periodic reports filed by ASPI with the U.S. Securities and Exchange Commission (the “SEC”), including but not limited to those described under the heading “Risk Factors” in its annual reports on Form 10-K, quarterly reports on Form 10-Q and any other filings made with the SEC from time to time, which are available via the SEC’s website at www.sec.gov. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those indicated or anticipated by these forward-looking statements. Therefore, you should not rely on any of these forward-looking statements.

Item 8.01. Other Events.

On November 27, 2025, ASP Isotopes and Renergen released a joint announcement on the Stock Exchange News Service of the JSE Limited captioned “Scheme of Arrangement – Extension of Outstanding Offer Conditions Fulfilment and Loan Repayment Date,” a copy of which is attached as Exhibit 99.1 hereto and is incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

Exhibit No.		Description
2.1		Letter Agreement, dated November 27, 2025, by and among ASP Isotopes Inc. and Renergen Limited.
10.1		Letter to the Term Loan Facility Agreement, dated November 27, 2025, by and among ASP Isotopes Inc., ASP Isotopes South Africa Proprietary Limited, as lender, and Renergen Limited, as borrower.
99.1		Joint Announcement released by Renergen and ASP Isotopes Inc. on the Stock Exchange News Service of the JSE Limited on November 27, 2025 regarding Scheme of Arrangement – Extension of Outstanding Offer Conditions Fulfilment and Loan Repayment Date.
104		Cover Page Interactive Date File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	ASP ISOTOPES INC.

Date: November 28, 2025	By:	/s/ Donald G. Ainscow
	Name:	Donald G. Ainscow
	Title:	Executive Vice President, General Counsel and Secretary

ASP Isotopes Inc. 8-K