UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of ~~May~~August 2025

Commission File Number: 001-40777

ARQIT QUANTUM INC.

(Exact name of registrant as specified in its charter)

1^st Floor, 3 Orchard Place

London, SW1H 0BF, United Kingdom

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:.

Form 20-F ☒    x Form 40-F ☐ ¨

EXPLANATORY NOTE

OnAttached ~~May 22,~~hereto ~~2025~~and ~~Arqit~~incorporated by ~~Quantum~~reference ~~Inc.~~herein ~~(“Arqit”)~~are ~~Arqit~~the ~~reported~~notice ~~its financial~~ and ~~operational~~proxy ~~results~~materials ~~for~~related to the ~~six~~Annual ~~months~~General ~~ended~~Meeting ~~March 31,~~of ~~2025.~~Shareholders ~~A copy~~ of ~~a press release~~ Arqit ~~issued in connection therewith entitled “Arqit~~ Quantum Inc. ~~Announces~~to be ~~Financial~~held ~~and~~on ~~Operational Results for the First Half of Fiscal Year 2025,” is attached as Exhibit~~September ~~99.1 hereto~~11, ~~Arqit’s unaudited condensed consolidated interim financial statements as of and for the six months ended March 31,~~ 2025 ~~are attached hereto as Exhibit 99~~.~~2 and management’s discussion and analysis of financial condition and results of operations for the six months ended March 31, 2025 is attached hereto as Exhibit 99.3.~~

On May 16, 2025, Arqit’s board of directors approved the appointment of chief executive officer Andrew Leaver as a Class II director, and the appointment of existing director Garth Richie as chairman. In connection with Mr. Leaver’s appointment, Nick Pointon agreed to tender his resignation as a director, however will continue to serve as Arqit’s chief financial officer. The changes to the board became effective on May 20, 2025.Exhibit List

Other than as indicated below, the information in this Report of Foreign Private Issuer on Form 6-K (including the exhibits hereto) 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 in any filing under the Securities Act of 1933, as amended, or the Exchange Act. The information furnished in Exhibit 99.2 and Exhibit 99.3 to this Report of Foreign Private Issuer on Form 6-K is hereby incorporated by reference into the Company’s registration statements on Form S-8 (File Nos. 333-262215, 333-275960 and 333-284706) and Form F-3 (File Nos. 333-268786, 333-259982 and 333-284343), and shall be a part thereof, to the extent not superseded by documents or reports subsequently filed or furnished.

Exhibit No.		Description

99.1		Notice and Proxy Materials for the 2025 Annual General Meeting of Arqit Quantum Inc.
99.2		Form of Proxy Card

EXHIBIT INDEX

ExhibitNo.		Description
99.1		Press release of Arqit Quantum Inc., dated May 22, 2025.
99.2		Unaudited Condensed Consolidated Interim Financial Statements as of and for the Six Months Ended March 31, 2025.
99.3		Management’s Discussion and Analysis for the Six Months Ended March 31, 2025.

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, thereunto duly authorized.

ARQIT QUANTUM INC. By: /s/ Andrew Leaver Name: Andrew Leaver Title: Chief Executive Officer

~~ARQIT QUANTUM INC. By~~Date: ~~/s/~~August 28, ~~Andrew Leaver Name: Andrew Leaver Title: Chief Executive Officer ~~2025

Date: May 22, 2025

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