Form 8-K

8-K — Actinium Pharmaceuticals, Inc.

Accession: 0001213900-26-062935

Filed: 2026-05-29

Period: 2026-05-27

CIK: 0001388320

SIC: 2834 (PHARMACEUTICAL PREPARATIONS)

Item: Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

Item: Regulation FD Disclosure

Item: Financial Statements and Exhibits

Documents

8-K — ea0292691-8k_actinium.htm (Primary)

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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):

May 27, 2026

ACTINIUM PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its

charter)

Delaware

001-36374

74-2659386

(State or other jurisdiction

of incorporation)

(Commission File Number)

(IRS Employer

Identification No.)

100 Park Ave.,

23rd Floor,

New

York, New York 10017

(Address of principal executive offices) (Zip

Code)

Registrant’s telephone number, including

area code: (646) 677-3870

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 $0.001 per share

ATNM

NYSE American 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 3.01. Notice of Delisting or Failure to Satisfy a Continued

Listing Rule or Standard; Transfer of Listing.

On May 27, 2026, Actinium Pharmaceuticals, Inc.

(the “Company”) received a notice (the “Notice”) from NYSE American LLC (“NYSE American”) indicating

that the Company is not in compliance with the continued listing standards set forth in Section 1003(a)(ii) of the NYSE American Company

Guide (the “Company Guide”), which requires a listed company to maintain stockholders’ equity of $4.0 million or more

if it has reported losses from continuing operations and/or net losses in three of its four most recent fiscal years. As of March 31,

2026, the Company reported stockholders’ equity of approximately $2.3 million, and had net losses in its last five fiscal years

ended December 31, 2025.

In connection with its non-compliance with Sections

1003(a)(ii) and (iii) of the Company Guide, the Company must submit a plan by June 26, 2026, advising of actions it has taken or will

take to regain compliance with the continued listing standards by November 27, 2027 (“Plan Period Deadline”). If NYSE Regulation

determines to accept the plan, the Company will be notified in writing and will be subject to periodic reviews including quarterly monitoring

for compliance with the plan.

If the Company does not submit a plan or if the

plan is not accepted, delisting proceedings will commence. Furthermore, if the plan is accepted but the Company is not in compliance with

the continued listing standards by the Plan Period Deadline, or if the Company does not make progress consistent with the plan during

the plan period, NYSE American staff will initiate delisting proceedings as appropriate. The Company may appeal a staff delisting determination

in accordance with Section 1010 and Part 12 of the Company Guide.

The Notice has no immediate effect on the listing

or trading of the Company’s common stock, which will continue to trade on NYSE American under the symbol “ATNM,” subject

to the Company’s compliance with the other continued listing requirements of NYSE American, and will continue to trade with a “.BC”

indicator to denote that the Company is below compliance. The Company intends to submit a plan to NYSE American within the required timeframe.

There can be no assurance that the Company will

be able to regain compliance with the applicable continued listing standards, that the Company will submit a plan that is accepted by

NYSE American, that the Company will be able to comply with the terms of any accepted Plan, or that the Company will be able to maintain

the listing of its common stock on NYSE American.

Item 7.01. Regulation FD Disclosure.

On May 29, 2026, pursuant to Sections 402(g) and 1009(j) of the Company

Guide, the Company issued a press release announcing, among other things, its receipt of the Notice and providing an update on the development

program for its ATNM-400 product candidate. The full text of the press release is set forth below.

The information furnished pursuant to this Item 7.01 shall not be deemed

“filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or

otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing under the Securities

Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.

Description

99.1

Press Release dated May 29, 2026 (furnished pursuant to Item 7.01 of Form 8-K)

104

Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURE

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.

ACTINIUM PHARMACEUTICALS, INC.

Date: May 29, 2026

By:

/s/ Sandesh Seth

Name:

Sandesh Seth

Title:

Chairman and Chief Executive Officer

EX-99.1 — PRESS RELEASE DATED MAY 29, 2026

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Exhibit 99.1

Actinium Pharmaceuticals

to Present ATNM-400 Program Update at SNMMI 2026 Conference on May 31-June 2 and Provides NYSE American Listing Standards Notice

NEW YORK, May 29, 2026 /PRNewswire/ -- Actinium

Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a leader in the development

of targeted radiotherapies, today announced it will provide a program update on its first-in-class Actinium-225 (225Ac) antibody radioconjugate,

ATNM-400, highlighting new data that will be showcased across three presentations at the Society of Nuclear Medicine and Molecular Imaging

(SNMMI) 2026 Annual Meeting, taking place May 30-June 2, 2026, in Los Angeles, California. Two of the presentations showcase ATNM-400’s

differentiated profile across prostate cancer and non-small cell lung cancer (NSCLC), while a third demonstrates the importance of radioconjugate

optimization for radiotherapies in the context of the Company’s pipeline candidates.

With the SNMMI 2026 program now finalized, the Company is providing

updated presentation details, including poster titles, presenters, dates, and times. The data to be presented reinforce the meaningful

progress of the ATNM-400 program and its potential as a mutation-agnostic, pan-tumor therapy, while also demonstrating the strength of

the underlying radioconjugate platform that supports Actinium’s broader pipeline. The Company anticipates multiple catalysts for

ATNM-400, Actimab-A and Iomab-ACT in 2H:2026 that are expected to demonstrate the clinical potential of these programs.

ATNM-400 SNMMI 2026 Presentation Details

Poster Title: ATNM-400: A First-in-Class

Non-PSMA Actinium-225 Antibody Radioconjugate Demonstrates Superior Efficacy to PSMA-617 Radioligands and ARPIs With Favorable Safety

Profile in Prostate Cancer Models

Presenter: Sumit Mukherjee Ph.D., Actinium

Pharmaceuticals, Inc.

Session: Oncology: Discovery & Translational

Meet the Author Session

Date & Time: Tuesday, June 2, 2026

11:30am-12:15pm PT | Los Angeles, California

Poster Title: ATNM-400: A First-in-Class

Actinium-225 Antibody Radioconjugate Demonstrating Durable, Mutation-Agnostic Anti-Tumor Activity in Non-Small Cell Lung Cancer Models

Presenter: Shiva Kazerounian Ph.D., Actinium

Pharmaceuticals, Inc.

Session: Oncology: Discovery & Translational

Meet the Author Session

Date & Time: Tuesday, June 2, 2026,

11:30am-12:15pm PT | Los Angeles, California

Poster Title: Optimizing Chelator-to-Antibody

Ratio Improves Tumor Targeting and Pharmacokinetics of 225Ac-Labeled Antibodies

Presenter: Shiva Kazerounian Ph.D., Actinium Pharmaceuticals, Inc.

Session: MTA05 RPSC/CMIIT POPs and Science

Pavilion Mixer

Date & Time: Sunday, May 31, 2026,

7:30-8:00pm PT | Los Angeles, California

The posters will be available on the Company website

shortly after the presentations at https://ir.actiniumpharma.com/presentations-webinars.

NYSE American Continued Listing Standards Notice

Actinium also announced today that it has received a notice (the “Notice”)

from the NYSE American LLC (“NYSE American”) indicating that the Company is not in compliance with the continued listing standards

set forth in Section 1003(a)(ii) of the NYSE American Company Guide (the “Company Guide”), which requires a listed company

to maintain stockholders’ equity of $4.0 million or more if it has reported losses from continuing operations and/or net losses in three

of its four most recent fiscal years. As of March 31, 2026, the Company reported stockholders’ equity of approximately $2.3 million and

had net losses in its last five fiscal years ended December 31, 2025. The Notice also indicates that the Company is also not currently

eligible for any exemption in Section 1003(a) of the Company Guide. The notice has no immediate effect on the listing or trading of the

Company’s common stock on the NYSE American and the Company’s shares will continue to trade under the symbol “ATNM,”

subject to compliance with other listing requirements of the Company Guide.

In connection with the non-compliance with Sections

1003(a)(ii) and (iii) of the Company Guide, the Company must submit a compliance plan by June 26, 2026, advising of actions the Company

has taken or will take to regain compliance with the continued listing standards by November 27, 2027 (the “Plan Period Deadline”).

If the NYSE American determines to accept the plan, the Company will be notified in writing and will be subject to periodic reviews, including

quarterly monitoring, for compliance with the plan.

If the Company does not submit a plan or if the plan is not accepted,

delisting proceedings will commence. Furthermore, if the plan is accepted but the Company is not in compliance with the continued listing

standards by the Plan Period Deadline which is eighteen months from the receipt of the notice or November 27, 2027, or if the Company

does not make progress consistent with the plan during the plan period, Exchange staff will initiate delisting proceedings as appropriate.

The Company may appeal a staff delisting determination in accordance with Section 1010 and Part 12 of the Company Guide.

Actinium currently intends to submit a plan to regain compliance within

the required timeframe. There can be no assurance that the Company will be able to achieve compliance with the NYSE American's continued

listing standards within the required timeframe of eighteen months from date of receipt of the notice or November 27, 2027.

About Actinium Pharmaceuticals, Inc.

Actinium is a pioneer in targeted radiotherapies

designed to improve outcomes for patients with cancer. The company employs a biology-driven approach to develop differentiated radiopharmaceuticals

for solid tumors and hematologic malignancies. Its mission is to transform cancer treatment through innovative radioconjugates that maximize

therapeutic efficacy while minimizing toxicity to healthy tissue by combining expertise in tumor biology, translational medicine, and

radiochemistry. Since inception, Actinium has focused on developing innovative radiotherapies. Its pipeline reflects this strategy across

three areas: (1) solid tumor therapeutics including ATNM-400 and Actimab-A with pan-tumor potential; (2) Actimab-A as a therapeutic backbone

for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in collaboration with the National Cancer Institute (NCI); and (3)

targeted conditioning agents including Iomab-B for bone marrow transplant and Iomab-ACT for cell and gene therapy conditioning. ATNM-400

targets a novel antigen distinct from PSMA and has demonstrated preclinical activity across metastatic castration-resistant prostate cancer

(mCRPC), non-small cell lung cancer (NSCLC), and breast cancer. Actimab-A has shown improved survival in relapsed/refractory AML with

CLAG-M and is advancing toward a Phase 2/3 trial, with additional development ongoing through a CRADA with the NCI. Actinium is also advancing

preclinical solid tumor programs and holds ~250 patents and patent applications, including intellectual property related to cyclotron-based

production of Ac-225. For more information, please visit www.actiniumpharma.com.

Forward-Looking Statements

This press release may contain projections or

other “forward-looking statements” within the meaning of the “safe-harbor” provisions of the private securities

litigation reform act of 1995 regarding future events or the future financial performance of the Company which the Company undertakes

no obligation to update. These statements, including statements as related to regaining compliance with the rules of the NYSE American

and submission of a compliance plan, are based on management’s current expectations and are subject to risks and uncertainties that

may cause actual results to differ materially from the anticipated or estimated future results, including the risks and uncertainties

associated with preliminary study results varying from final results, estimates of potential markets for drugs under development, clinical

trials, actions by the FDA and other governmental agencies, regulatory clearances, responses to regulatory matters, the market demand

for and acceptance of Actinium’s products and services, performance of clinical research organizations and other risks detailed

from time to time in Actinium’s filings with the Securities and Exchange Commission (the “SEC”), including without limitation

its most recent annual report on form 10-K, subsequent quarterly reports on Forms 10-Q and Forms 8-K, each as amended and supplemented

from time to time.

Investors: investorrelations@actiniumpharma.com

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