ASP Isotopes (NASDAQ: ASPI) notifies SEC of late FY2025 10-K filing

Rhea-AI Filing Summary

ASP Isotopes Inc. submitted a Form 12b-25 notification stating it could not file its annual report on Form 10-K for the period ended December 31, 2025 within the prescribed time. The company signed the notice on March 31, 2026 and cites Rule 12b-25 procedures.

Key Figures

Period ended: December 31, 2025 Notice signed: March 31, 2026 Estimated burden hours: 2.50 hours +3 more

6 metrics

Period ended December 31, 2025 annual report period

Notice signed March 31, 2026 date of Form 12b-25 signature

Estimated burden hours 2.50 hours average hours per response on form

Form expiry September 30, 2028 OMB expiration date on form

SEC file number 001-41555 registrant SEC file number on cover

CUSIP 00218A105 CUSIP number listed on form

Key Terms

Form 12b-25, Rule 12b-25, Notification of Late Filing

3 terms

Form 12b-25 regulatory

"Notification of Late Filing; Rule 12b-25(b) and (c) referenced"

Form 12b-25 is a notice a publicly traded company files with the U.S. Securities and Exchange Commission when it cannot deliver a required periodic report (like a quarterly or annual financial report) on time. It explains the reason for the delay and gives the company a short, temporary window to finish the report without being marked as delinquent; investors watch it because late filings can signal accounting, operational, or control issues that may affect a company’s reliability and stock risk, much like a missed homework deadline can raise concerns about a student’s preparedness.

Rule 12b-25 regulatory

"Part II - Rules 12b-25(b) and (c) explanation"

Rule 12b-25 is an SEC filing provision that lets a company notify regulators and the public that it cannot file a required periodic report (like a quarterly or annual report) on time and explains the reason for the delay. For investors, the notice is a formal heads-up that financial information will arrive late—similar to a company calling to say it will be late turning in homework—so it signals increased uncertainty and may affect trading and risk assessments until the filing is available.

Notification of Late Filing regulatory

"Title line: NOTIFICATION OF LATE FILING"

		OMB APPROVAL
		OMB Number: 3235-0058
	UNITED STATES SECURITIES AND EXCHANGE COMMISSION	Expires: September 30, 2028
		Estimated average burden
	Washington, D.C. 20549	hours per response.......2.50
	FORM 12b-25	SEC FILE NUMBER
		001-41555
		CUSIP NUMBER
	NOTIFICATION OF LATE FILING	00218A105

(Check one):

☒

Form 10-K

☐

Form 20-F

☐

Form 11-K

☐

Form 10-Q

☐

Form 10-D

☐

Form N-CEN

☐

Form N-CSR

For Period Ended: December 31, 2025

☐

Transition Report on Form 10-K

☐

Transition Report on Form 20-F

☐

Transition Report on Form 11-K

☐

Transition Report on Form 10-Q

For the Transition Period Ended: __________________________________________

Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.

If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:

PART I - REGISTRANT INFORMATION

ASP Isotopes Inc.

Full Name of Registrant

Former Name if Applicable

2200 Ross Avenue, Suite 4575E

Address of Principal Executive Office (Street and Number)

Dallas, TX 75201

City, State and Zip Code

PART II - RULES 12b-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate)

☒	(a)	The reason described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense;
	(b)	The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, Form 11-K, Form N-CEN or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or subject distribution report on Form 10-D, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and
	(c)	The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.

PART III - NARRATIVE

State below in reasonable detail the reasons why Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-CEN, N-CSR, or the transition report or portion thereof, could not be filed within the prescribed time period.

(Attach extra Sheets if Needed)

The Registrant could not complete the filing of its Annual Report on Form 10-K for the year ended December 31, 2025, due to a delay in obtaining and compiling information required to be included in its Form 10-K, which delay could not be eliminated by the Registrant without unreasonable effort and expense. In accordance with Rule 12b-25 promulgated under the Securities Exchange Act of 1934, as amended, the Registrant will file its Form 10-K no later than the fifteenth calendar day following the prescribed due date.

PART IV - OTHER INFORMATION

(1) Name and telephone number of person to contact in regard to this notification

Heather Kiessling		(214)		432-8219
(Name)		(Area Code)		(Telephone Number)

(2)	Have all other periodic reports required under Section 13 or 15(d) of the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed? If answer is no, identify report(s). Yes ☒ No ☐
(3)	Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof? Yes ☐ No ☒
	If so, attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made.

2

ASP Isotopes Inc.

(Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned hereunto duly authorized.

Date: March 31, 2026	By:	/s/ Heather Kiessling
		Heather Kiessling
		Chief Financial Officer

3

FAQ

Why did ASP Isotopes (ASPI) file a Form 12b-25?

They filed to notify regulators of a late Form 10-K filing under Rule 12b-25. The notice identifies the period ended December 31, 2025 and is signed on March 31, 2026, seeking the allowed extension process.

What timing does the Form 12b-25 allow for ASP Isotopes' late 10-K?

The form allows a limited extension to file the delayed report: up to 15 calendar days for annual reports. The company checked Rule 12b-25 provisions and followed required procedure.

Does the Form 12b-25 say ASP Isotopes will miss other periodic filings?

The notice includes a checkbox asking whether other periodic reports have been filed. The form does not list any additional missed reports in the provided excerpt.

Who signed ASP Isotopes' Form 12b-25 and what is their role?

Heather Kiessling, Chief Financial Officer, signed the notification on March 31, 2026. A contact phone number is provided on the form for follow-up.

What period does the late filing relate to for ASPI's Form 10-K?

The late filing notification specifically relates to the annual period ended December 31, 2025. The form identifies that reporting period as the subject of the delayed 10-K.