Plum Acquisition IV (NASDAQ: PLMK) extends Controlled Thermal Resources merger timelines

Rhea-AI Filing Summary

Plum Acquisition Corp. IV entered Amendment No. 1 to its Business Combination Agreement with Controlled Thermal Resources Holdings Inc. and Plum IV Merger Sub Inc. The amendment mainly pushes back several closing-related deadlines for their planned merger.

The Company now has until June 15, 2026 to deliver required financial statements and until June 30, 2026 to provide pro forma financial information for inclusion in the proxy statement/prospectus. The deadline for required antitrust filings was moved to July 31, 2026, and dates for delivering certain material consents were also extended. The filing reiterates that a Form S-4 registration statement and combined proxy statement/prospectus will be submitted to the SEC for shareholder approval of the transaction.

8-K Event Classification

2 items: 1.01, 9.01

2 items

Item 1.01 Entry into a Material Definitive Agreement Business

The company signed a significant contract such as a merger agreement, credit facility, or major partnership.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, and exhibit attachments filed with this report.

Key Figures

Class A par value: $0.0001 per share Warrant exercise price: $11.50 per share Financial statements deadline: June 15, 2026 +4 more

7 metrics

Class A par value $0.0001 per share Par value of Class A ordinary shares

Warrant exercise price $11.50 per share Each whole warrant exercisable for one Class A ordinary share

Financial statements deadline June 15, 2026 Extended date to deliver required financial statements for proxy/prospectus

Pro forma information deadline June 30, 2026 Extended date to deliver pro forma financial information

Antitrust filing deadline July 31, 2026 Extended date to make required antitrust filings for the transaction

Original financials deadline May 15, 2026 Prior deadline for Company financial statements before extension

Original material consents date May 7, 2026 Prior date to deliver certain material consents before extension

Key Terms

Business Combination Agreement, Registration Statement on Form S-4, Proxy Statement/Prospectus, emerging growth company, +1 more

5 terms

Business Combination Agreement financial

"entered into a Business Combination Agreement (the “Business Combination Agreement”"

A business combination agreement is a detailed contract that lays out the terms for two companies to join together—covering price, how ownership will be split, the steps needed to close the deal, and what each side promises to do or avoid before closing. For investors it matters because the agreement determines potential changes in value, control, timing, and risk exposure—think of it like the playbook for a merger that shows who wins, who pays, and what could still derail the plan.

Registration Statement on Form S-4 regulatory

"intend to file with the SEC a registration statement on Form S-4 (the “Registration Statement”)"

A registration statement on Form S-4 is a formal filing with the U.S. Securities and Exchange Commission used when a company issues shares or other securities as part of a merger, acquisition, exchange offer or similar corporate deal. It bundles the transaction terms, financial statements, risk factors and shareholder vote materials so investors can assess the deal; think of it as a detailed prospectus or buyer’s packet that explains what you would own and how the deal could change your stake.

Proxy Statement/Prospectus regulatory

"a preliminary proxy statement of Plum IV as well as a preliminary prospectus ... (the “Proxy Statement/Prospectus”)"

A proxy statement or prospectus is a document that companies send to shareholders to provide important information about upcoming decisions or investments, such as voting on company issues or offering new shares to the public. It helps investors understand the details and risks involved, enabling them to make informed choices about their ownership or involvement with the company.

emerging growth company regulatory

"Emerging growth company"

An emerging growth company is a recently public or smaller public firm that qualifies for temporary, lighter regulatory and disclosure rules to reduce the cost and effort of being public. For investors, it means the company may provide less historical financial detail and face fewer reporting requirements than larger firms, so it can grow more quickly but also carries higher uncertainty—like buying a promising early-stage product with fewer user reviews.

forward-looking statements financial

"contain certain forward-looking statements within the meaning of the U.S. federal securities laws"

Forward-looking statements are predictions or plans that companies share about what they expect to happen in the future, like estimating sales or profits. They matter because they help investors understand a company's outlook, but since they are based on guesses and assumptions, they can sometimes be wrong.

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Understanding 8-K Material Events →

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

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

Date of Report (Date of earliest event reported): May 18, 2026 (May 15, 2026)

PLUM ACQUISITION CORP. IV

(Exact name of registrant as specified in its charter)

Cayman Islands		001-42472		98-1795710
(State or other jurisdiction of incorporation or organization)		(Commission File Number)		(I.R.S. Employer Identification Number)

2021 Fillmore St. #2089 San Francisco, California		94115
(Address of principal executive offices)		(Zip Code)

Registrant’s telephone number, including area code: (929) 529-7125 

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 to 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
Units, each consisting of one Class A ordinary share, par value $0.0001 per share, and one-half of one redeemable warrant		PLMKU		Nasdaq Global Market
Class A ordinary shares, par value $0.0001 per share, included as part of the units		PLMK		Nasdaq Global Market
Warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50		PLMKW		Nasdaq Global Market

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

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.

As previously disclosed, on March 8, 2026, Plum Acquisition Corp. IV, a Cayman Islands exempted company (which will transfer by way of continuation from the Cayman Islands to the State of Delaware and domesticate as a Delaware corporation prior to the Closing (as defined below)) (“Plum IV”), Plum IV Merger Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary of Plum IV (“Merger Sub”), and Controlled Thermal Resources Holdings Inc., a Delaware corporation (the “Company”) entered into a Business Combination Agreement (the “Business Combination Agreement”, and the transactions contemplated thereby, the “Transactions”), pursuant to which, among other things and subject to the terms and conditions contained therein, Merger Sub will merge with and into the Company, with the Company continuing as the surviving company.

On May 15, 2026, Plum IV, the Company and Merger Sub entered into an amendment to the Business Combination Agreement (the “BCA Amendment”), which amends the Business Combination Agreement to, among other things, (i) extend the date by which the Company is required to deliver financial statements and pro forma financial information of the Company required to be included in the proxy statement/prospectus from May 15, 2026 to June 15, 2026 and June 30, 2026, respectively; (ii) extend the date by which Plum IV, the Company and Merger Sub are required to make any filings or applications required under antitrust laws with respect to the Transactions from April 17, 2026 to July 31, 2026; and (iii) extend the dates by which the Company is required to deliver certain material consents from May 7, 2026 to the dates listed on Schedule 8.01(m) to the Business Combination Agreement.

The foregoing description of the form of the BCA Amendment does not purport to be complete and is qualified in its entirety by reference to the full text of the BCA Amendment, a copy of which is filed as Exhibit 10.1 to this Current Report on Form 8-K (“Current Report”), and incorporated herein by reference.

Additional Information and Where to Find It

In connection with the Transactions, Plum IV and the Company intend to file with the SEC a registration statement on Form S-4 (the “Registration Statement”), which will include a preliminary proxy statement of Plum IV as well as a preliminary prospectus relating to the offer of securities to be issued to the stockholders of the Company (the “Proxy Statement/Prospectus”). After the Registration Statement is declared effective, a definitive proxy statement and other relevant documents will be mailed to shareholders of Plum IV as of the record date to be established for voting on the Transactions and other matters as described in the Proxy Statement/Prospectus. Plum IV will also file other documents regarding the Transactions with the SEC. This Current Report does not contain all of the information that should be considered concerning the Transactions and is not intended to form the basis of any investment decision or any other decision in respect of the Transactions. BEFORE MAKING ANY VOTING OR INVESTMENT DECISION, SHAREHOLDERS OF PLUM IV AND OTHER INTERESTED PARTIES ARE URGED TO READ, WHEN AVAILABLE, THE PRELIMINARY PROXY STATEMENT/PROSPECTUS, AND AMENDMENTS THERETO, AND THE DEFINITIVE PROXY STATEMENT/PROSPECTUS AND ALL OTHER RELEVANT DOCUMENTS FILED OR THAT WILL BE FILED WITH THE SEC IN CONNECTION WITH PLUM IV’S SOLICITATION OF PROXIES FOR THE EXTRAORDINARY GENERAL MEETING OF ITS SHAREHOLDERS TO BE HELD TO APPROVE THE TRANSACTIONS AND OTHER MATTERS AS DESCRIBED IN THE PROXY STATEMENT/PROSPECTUS BECAUSE THESE DOCUMENTS WILL CONTAIN IMPORTANT INFORMATION ABOUT PLUM IV, the Company AND THE TRANSACTIONS. Investors and security holders will also be able to obtain copies of the Registration Statement and the Proxy Statement/Prospectus and all other documents filed or to be filed with the SEC by Plum IV, without charge, once available, on the SEC’s website at www.sec.gov or by directing a request to: Plum Acquisition Corp. IV, 2021 Fillmore St., #2089, San Francisco, California 94115, Attention: Kanishka Roy, or by email at plumir@icrinc.com.

1

Participants in the Solicitation

Plum IV, the Company and their respective directors and executive officers may be deemed participants under SEC rules in the solicitation of proxies from Plum IV’s shareholders in connection with the Transactions. A list of the names of such directors and executive officers and information regarding their interests in the Transactions and their ownership of Plum IV’s securities is, or will be, contained in Plum IV’s filings with the SEC. Additional information regarding the interests of the persons who may, under SEC rules, be deemed participants in the solicitation of proxies from Plum IV’s shareholders in connection with the Transactions, including the names and interests of the Company’s directors and executive officers, will be set forth in the Proxy Statement/Prospectus, which is expected to be filed by Plum IV and the Company with the SEC. Investors and security holders may obtain free copies of these documents as described above.

No Offer or Solicitation

This Current Report is for informational purposes only and is not a proxy statement or solicitation of a proxy, consent or authorization with respect to any securities or in respect of the Transactions and shall not constitute an offer to sell or exchange, or a solicitation of an offer to buy or exchange the securities of Plum IV or the Company, or any commodity or instrument or related derivative, nor shall there be any sale of any such securities in any state or jurisdiction in which such offer, solicitation, sale or exchange would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction. This Current Report is not, and under no circumstances is to be construed as, a prospectus, an advertisement or a public offering of the securities described herein in the United States or any other jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of the Securities Act or an exemption therefrom. Investors should consult with their counsel as to the applicable requirements for a purchaser to avail itself of any exemption under the Securities Act.

Forward-Looking Statements

This Current Report and the exhibits attached hereto contain certain forward-looking statements within the meaning of the U.S. federal securities laws with respect to the Transactions and the parties thereto. All statements contained in this Current Report other than statements of historical fact, including, without limitation, statements regarding the Transactions between Plum IV and the Company; the anticipated benefits and timing of the Transactions; expected trading of the combined company’s securities on the Nasdaq; the building of the Company’s flagship Hell’s Kitchen Project; the anticipated benefits and timing of the Company’s flagship Hell’s Kitchen Project, the combined company’s future financial performance; the ability of the combined company to execute its business strategy, its market opportunity and positioning; and other statements regarding management’s intentions, beliefs, or expectations with respect to the combined company’s future performance, are forward-looking statements.

Forward-looking statements are often identified by the use of words such as “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “should,” “will,” “would,” and similar expressions, but the absence of these words does not mean that a statement is not forward-looking.

2

These forward-looking statements are based on the current expectations and assumptions of Plum IV and the Company and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such forward-looking statements. Such risks and uncertainties include, but are not limited to: (1) the occurrence of any event, change or other circumstances that could give rise to the termination of the Business Combination Agreement; (2) the outcome of any legal proceedings that may be instituted against the parties following the announcement of the Transactions and any definitive agreements with respect thereto; (3) the inability to complete the Transactions, including due to failure to obtain approval of the shareholders of Plum IV and the Company or other conditions to closing; (4) the risk that the Transactions may not be completed by Plum IV’s business combination deadline and the potential failure to obtain an extension of the business combination deadline if sought by Plum IV; (5) the inability to maintain the listing of Plum IV’s securities or to obtain or maintain the listing of the combined company’s securities on the Nasdaq, the New York Stock Exchange, or another national securities exchange following the Transactions; (6) the risk that the Transactions disrupts the Company’s current plans, business relationships, performance, operations and business generally as a result of the announcement and consummation of the Transactions; (7) the risk that the price of the combined company’s securities may be volatile due to a variety of factors, including changes in laws, regulations, technologies, natural disasters, geopolitical tensions, and macro-economic and social environments affecting its business; (8) the ability to recognize the anticipated benefits of the Transactions, which may be affected by, among other things, competition, the ability of the combined company to grow and manage growth profitably and retain its key employees; (9) costs related to the Transactions; (10) changes in applicable laws or regulations; (11) risks related to the Company’s business, including fluctuations in demand and prices for lithium and other critical minerals, competition within the industry, the risks inherent in development projects and exploration activities, potential delays or cost overruns in capital expenditures, the ability to secure necessary raw materials, compliance with regulatory requirements, environmental and safety obligations, economic and market conditions, and political or geopolitical developments; and (12) other risks detailed from time to time in Plum IV’s filings with the SEC, including the Registration Statement and related documents filed or to be filed in connection with the Transactions.

The foregoing list of risk factors is not exhaustive. You should carefully consider the foregoing factors and the other risks and uncertainties described in the “Risk Factors” section of Plum IV’s Annual Report on Form 10-K filed with the SEC on March 31, 2026, Plum IV’s Quarterly Report on Form 10-Q filed with the SEC on May 15, 2026, subsequent Quarterly Reports on Form 10-Q and the Registration Statement and Proxy Statement/Prospectus that will be filed by Plum IV and the Company, and other documents filed by Plum IV from time to time with the SEC, as well as the list of risk factors included herein. These filings identify and address other important risks and uncertainties that could cause actual results to differ materially from those contained in the forward-looking statements. Additional risks and uncertainties not currently known or that are currently deemed immaterial may also cause actual results to differ materially from those expressed or implied by such forward-looking statements. Readers are cautioned not to put undue reliance on forward-looking statements, and none of the parties or any of their representatives assumes any obligation and do not intend to update or revise these forward-looking statements, each of which is made only as of the date of this Current Report.

Item 9.01. Financial Statements and Exhibits.

(c) Exhibits.

Exhibit No.		Description
10.1†		Amendment No. 1 to the Business Combination Agreement, dated May 15, 2026, by and among Plum Acquisition Corp. IV, Plum IV Merger Sub Inc. and Controlled Thermal Resources Holdings Inc.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document)

† Certain of the exhibits and schedules to this exhibit have been omitted in accordance with Regulation S-K Item 601(b)(2). The Registrant agrees to furnish supplementally a copy of all omitted exhibits and schedules to the SEC upon its request.

3

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.

Date: May 18, 2026	PLUM ACQUISITION CORP. IV
	By:	/s/ Kanishka Roy
	Name:	Kanishka Roy
	Title:	Chief Executive Officer

4

FAQ

What did Plum Acquisition Corp. IV (PLMK) disclose in this 8-K?

Plum Acquisition Corp. IV disclosed an amendment to its Business Combination Agreement with Controlled Thermal Resources Holdings Inc., mainly extending key deadlines for financial statements, antitrust filings, and material consents tied to their planned merger and upcoming shareholder vote.

How does the BCA Amendment change PLMK’s merger timeline?

The amendment extends the Company’s deadline to deliver required financial statements to June 15, 2026 and pro forma financial information to June 30, 2026, and moves the antitrust filing deadline to July 31, 2026, giving more time to complete regulatory and disclosure preparations.

What regulatory filings are planned for the Plum IV and CTR merger?

Plum IV and Controlled Thermal Resources plan to file a registration statement on Form S-4 with the SEC containing a proxy statement/prospectus. After effectiveness, a definitive proxy statement and related materials will be mailed to Plum IV shareholders for approval of the business combination and related matters.

How can PLMK shareholders access the merger proxy materials?

Shareholders will receive the definitive proxy statement/prospectus by mail after SEC effectiveness. They can also obtain copies of the registration statement and proxy statement/prospectus free of charge from the SEC’s website or by contacting Plum Acquisition Corp. IV at its San Francisco address or investor relations email.

Does this PLMK filing constitute an offer of securities?

No. The filing states it is for informational purposes only and is not a prospectus or an offer to sell or solicit an offer to buy any securities. Any offer will be made only through a prospectus meeting Securities Act requirements or an applicable exemption.

What risks does PLMK highlight regarding completion of the CTR business combination?

The company cites risks including potential termination of the Business Combination Agreement, failure to obtain shareholder approvals, not meeting the SPAC deadline, listing issues, legal proceedings, transaction-related disruptions, market volatility, and operational risks tied to Controlled Thermal Resources’ lithium and critical minerals development business.

Filing Exhibits & Attachments

5 documents

Agreements & Contracts

• EX-10.1 AMENDMENT NO. 1 TO THE BUSINESS COMBINATION AGREEMENT, DATED MAY 15, 2026, BY AN 26.1 KB

Other Documents

• EX-101 XBRL SCHEMA FILE 4.2 KB
• EX-101 XBRL DEFINITION FILE 26.9 KB
• EX-101 XBRL LABEL FILE 37.4 KB
• EX-101 XBRL PRESENTATION FILE 25.5 KB