ARQQ / Arqit Quantum Inc. - SEC-Einreichungen, Jahresbericht, Proxy Statement

Arqit Quantum Inc.

Basisstatistiken
CIK 1859690
SEC Filings
All companies that sell securities in the United States must register with the Securities and Exchange Commission (SEC) and file reports on a regular basis. These reports include company annual reports (10K, 10Q), news updates (8K), investor presentations (found in 8Ks), insider trades (form 4), ownership reports (13D, and 13G), and reports related to the specific securities sold, such as registration statements and prospectus. This page shows recent SEC filings related to Arqit Quantum Inc.
SEC Filings (Chronological Order)
Auf dieser Seite finden Sie eine vollständige, chronologische Liste der SEC-Einreichungen, mit Ausnahme der Eigentumseinreichungen, die wir an anderer Stelle bereitstellen.
May 21, 2026 6-K

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 2026 Commission File Number: 001-40777

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 2026 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 2nd Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of princ

May 21, 2026 EX-99.2

Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements For the period ended 31 March 2026

Table of Contents Exhibit 99.2 Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements For the period ended 31 March 2026 Table of Contents Arqit Quantum Inc. Unaudited Condensed Consolidated Financial Statements as of and for the period ended 31 March 2026 Contents Page Condensed Consolidated Statement of Comprehensive Income (unaudited) 3 Condensed Consolidated Statement

May 21, 2026 EX-99.1

Arqit Quantum Inc.

Exhibit 99.1 Arqit Quantum Inc. Announces Financial Results for First Half of Fiscal Year 2026 London, UK – 21 May 2026 Arqit Quantum Inc. (Nasdaq: ARQQ) (“Arqit” or the “Company”), a global leader in quantum-safe encryption, announces financial results for the first half of fiscal year 2026. ● Consistent with management’s preliminary assessment of the expected range of revenue, which was announce

May 21, 2026 424B3

Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 PROSPECTUS SUPPLEMENT (To Prospectus dated November 22, 2022) Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated November 22, 2022 (the “Prospectus”) cove

May 21, 2026 EX-99.3

Results of Operations of Arqit Quantum Inc., (“Arqit” or the “Company”)

Exhibit 99.3 Results of Operations of Arqit Quantum Inc., (“Arqit” or the “Company”) Comparison of the Six Months Ended March 31, 2026 and 2025 Revenue Revenue increased by $556 thousand from $67 thousand for the six months ended March 31, 2025 to $623 thousand for the six months ended March 31, 2026. The increase was due to an increase in the number of customer contracts and the commencement of s

May 1, 2026 6-K

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 2026 Commission File Number: 001-40777

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 2026 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 2nd Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of princ

April 13, 2026 6-K

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 April 2026 Commission File Number: 001-4077

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 April 2026 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 2nd Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of pri

April 13, 2026 EX-99.1

Arqit Quantum Inc.

Exhibit 99.1 Arqit Quantum Inc. Announces Select Preliminary Financial Results for the First Half of Fiscal Year 2026 London, UK – 10 April 2026 Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (“Arqit”), a global leader in quantum-safe encryption, announces select preliminary financial results for the first half of fiscal year 2026. Based on preliminary unaudited results, management expects revenue for t

March 4, 2026 6-K

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 March 2026 Commission File Number: 001-4077

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 March 2026 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 2nd Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of pri

January 26, 2026 424B5

Arqit Quantum Inc Up to $125,000,000 Ordinary Shares

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration No. 333-292677 PROSPECTUS SUPPLEMENT (To Prospectus dated January 26, 2026) Arqit Quantum Inc Up to $125,000,000 Ordinary Shares We have entered into an At The Market Offering Agreement, dated January 12, 2026 (the “sales agreement”), with Cantor Fitzgerald & Co. and H.C. Wainwright & Co., LLC (the “sales agents”), relating to ordin

January 23, 2026 EX-FILING FEES

Security Type

Calculation of Filing Fee Tables F-3 Arqit Quantum Inc. Table 1: Newly Registered and Carry Forward Securities ☐Not Applicable Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee Carry Forward Form Type Carry Forward File Number Carry Forward Initial

January 23, 2026 F-3/A

As filed with the Securities and Exchange Commission on January 23, 2026

As filed with the Securities and Exchange Commission on January 23, 2026 Registration No.

January 12, 2026 EX-1.2

AT THE MARKET OFFERING AGREEMENT January 12, 2026

Exhibit 1.2 AT THE MARKET OFFERING AGREEMENT January 12, 2026 Cantor Fitzgerald & Co. 110 East 59th Street New York, NY 10022 H.C. Wainwright & Co., LLC 430 Park Avenue New York, NY 10022 Ladies and Gentlemen: Arqit Quantum Inc., a Cayman Islands corporation (the “Company”), confirms its agreement (this “Agreement”) with Cantor Fitzgerald & Co. (“Cantor”) and H.C. Wainwright & Co., LLC (“Wainwrigh

January 12, 2026 F-3

As filed with the Securities and Exchange Commission on January 12, 2026

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on January 12, 2026 Registration No.

January 12, 2026 EX-4.2

ARQIT QUANTUM INC., as issuer as trustee Dated as of [●], [●] TABLE OF CONTENTS

Exhibit 4.2 FORM OF INDENTURE ARQIT QUANTUM INC., as issuer and [●], as trustee INDENTURE Dated as of [●], [●] TABLE OF CONTENTS ARTICLE I DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.01 Definitions 1 Section 1.02 Other Definitions 4 Section 1.03 Incorporation by Reference of Trust Indenture Act 4 Section 1.04 Rules of Construction 4 ARTICLE II THE SECURITIES 5 Section 2.01 Issuable in S

January 12, 2026 6-K

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 January 2026 Commission File Number: 001-40

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 January 2026 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 2nd Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of p

January 12, 2026 EX-FILING FEES

Security Type

Calculation of Filing Fee Tables F-3 Arqit Quantum Inc. Table 1: Newly Registered and Carry Forward Securities ☐Not Applicable Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee Carry Forward Form Type Carry Forward File Number Carry Forward Initial

December 9, 2025 424B3

Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 PROSPECTUS SUPPLEMENT (To Prospectus dated November 22, 2022) Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated November 22, 2022 (the “Prospectus”) cove

December 9, 2025 EX-15.1

Consent of Independent Registered Public Accounting Firm

Exhibit 15.1 Consent of Independent Registered Public Accounting Firm We hereby consent to the incorporation by reference in the following Arqit Quantum Inc. registration statements: (1)registration statement on Form S-8 (File No. 333-262215); (2)registration statement on Form S-8 (File No. 333-275960); (3)registration statement on Form S-8 (File No. 333-284706); (4)registration statement on Form

December 9, 2025 EX-19.1

Arqit Quantum Inc. INSIDER TRADING POLICY

Exhibit 19.1 Arqit Quantum Inc. INSIDER TRADING POLICY This document sets forth the Insider Trading Policy (the “Policy”) of Arqit Quantum Inc. and its direct and indirect subsidiaries (collectively, “Arqit”). The Policy establishes the policies and procedures that govern trading by Arqit personnel in Arqit securities. The securities of any other company about which such personnel learns material,

December 9, 2025 EX-13.1

Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Exhibit 13.1 Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2025 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Andrew Leaver, Chief Executive Officer of the Company, certify,

December 9, 2025 6-K

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 December 2025 Commission File Number: 001-4

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 December 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of

December 9, 2025 EX-12.1

Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

Exhibit 12.1 Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Andrew Leaver, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in ligh

December 9, 2025 20-F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended September 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EX

December 9, 2025 EX-99.1

Arqit Quantum Inc.

Exhibit 99.1 Arqit Quantum Inc. Announces Financial Results for Fiscal Year 2025 London, UK – 9 December 2025 Arqit Quantum Inc. (Nasdaq: ARQQ) (“Arqit” or the “Company”), a global leader in quantum-safe encryption, announces financial results for the fiscal year ended 30 September 2025. · Consistent with management’s preliminary assessment of the expected range of revenue which was announced 9 Oc

December 9, 2025 EX-2.10

DESCRIPTION OF SECURITIES

Exhibit 2.10 DESCRIPTION OF SECURITIES The following description of the material terms of the securities of Arqit Quantum Inc. includes a summary of specified provisions of the Memorandum and Articles of association of the Company (the “Articles) and the forms of the warrants described herein. This description is subject to and qualified in its entirety by reference to the Articles and the forms o

December 9, 2025 EX-12.2

Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

Exhibit 12.2 Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Nick Pointon, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light

December 9, 2025 EX-13.2

Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Exhibit 13.2 Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2025 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Nick Pointon, Chief Financial Officer of the Company, certify,

December 9, 2025 424B3

Arqit Quantum Inc. 11,514,816 Ordinary Shares Offered by Selling Securityholders 5,440,000 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-289939 PROSPECTUS SUPPLEMENT (To Prospectus dated September 19, 2025) Arqit Quantum Inc. 11,514,816 Ordinary Shares Offered by Selling Securityholders 5,440,000 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated September 19, 2025 (the “Prospectus”) covering th

October 21, 2025 6-K

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 October 2025 Commission File Number: 001-40

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 October 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of p

October 9, 2025 EX-99.1

Arqit Quantum Inc.

Exhibit 99.1 Arqit Quantum Inc. Announces Select Preliminary Financial Results for the Second Half and Full Fiscal Year 2025 London, UK – 9 October 2025 Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (“Arqit”), a global leader in quantum-safe encryption, announces select preliminary financial results for the second half and full fiscal year 2025. Based on preliminary unaudited results, management expect

October 9, 2025 6-K

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 October 2025 Commission File Number: 001-40

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 October 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of p

October 6, 2025 144

144

144 0001967068 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Feenan Paul Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1158 56952.41 11545354 10/06/2025 NASDAQ Common 10/03/2025 Restricted Stock Vesting Issuer N 1158 10/03/2025 Compensation N Paul Feenan 3 Orchard Place London X0 SW1H 0BF Common 07/07/

October 6, 2025 144

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144 0001967201 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Pointon Nicholas Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1409 69297.02 11545354 10/06/2025 NASDAQ Common 10/03/2025 Restricted Stock Vesting Issuer N 1409 10/03/2025 Compensation N Nicholas Pointon 3 Orchard Place London X0 SW1H 0BF Com

October 6, 2025 144

144

144 0001967066 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Shiu Daniel Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 859 42247.07 11545354 10/06/2025 NASDAQ Common 10/03/2025 Restricted Stock Vesting Issuer N 859 10/03/2025 Compensation N Daniel Shiu 3 Orchard Place London X0 SW1H 0BF Common 09/03/20

October 6, 2025 144

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144 0001967211 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Willcocks Patrick Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1419 69788.83 11545354 10/06/2025 NASDAQ Common 10/03/2025 Restricted Stock Vesting Issuer N 1419 10/03/2025 Compensation N Patrick Willcocks 3 Orchard Place London X0 SW1H 0BF C

October 6, 2025 144

144

144 0002035890 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Leaver Andrew Officer Director Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 796 39148.63 11545354 10/06/2025 NASDAQ Common 10/03/2025 Restricted Stock Vesting Issuer N 796 10/03/2025 Compensation N Andrew J. Leaver 3 Orchard Place London X0 SW1H 0BF

October 3, 2025 144

144

144 0001967211 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Willcocks Patrick Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1353 67893.13 11545354 10/03/2025 NASDAQ Common 10/02/2025 Restricted Stock Vesting Issuer N 1353 10/02/2025 Compensation N Patrick Willcocks 3 Orchard Place London X0 SW1H 0BF C

October 3, 2025 144

144

144 0001967068 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Feenan Paul Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1105 55448.57 11545354 10/03/2025 NASDAQ Common 10/02/2025 Restricted Stock Vesting Issuer N 1105 10/02/2025 Compensation N Paul Feenan 3 Orchard Place London X0 SW1H 0BF Common 07/07/

October 3, 2025 144

144

144 0001967201 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Pointon Nicholas Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1345 67491.69 11545354 10/03/2025 NASDAQ Common 10/02/2025 Restricted Stock Vesting Issuer N 1345 10/02/2025 Compensation N Nicholas Pointon 3 Orchard Place London X0 SW1H 0BF Com

October 3, 2025 144

144

144 0002035890 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Leaver Andrew Officer Director Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 760 38136.57 11545354 10/03/2025 NASDAQ Common 10/02/2025 Restricted Stock Vesting Issuer N 760 10/02/2025 Compensation N Andrew J. Leaver 3 Orchard Place London X0 SW1H 0BF

October 3, 2025 144

144

144 0001967066 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Shiu Daniel Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 820 41147.36 11545354 10/03/2025 NASDAQ Common 10/02/2025 Restricted Stock Vesting Issuer N 820 10/02/2025 Compensation N Daniel Shiu 3 Orchard Place London X0 SW1H 0BF Common 09/03/20

October 2, 2025 144

144

144 0001967068 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Feenan Paul Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1091 47034.10 11545354 10/02/2025 NASDAQ Common 10/01/2025 Restricted Stock Vesting Issuer N 1091 10/01/2025 Compensation N Paul Feenan 3 Orchard Place London X0 SW1H 0BF Common 07/07/

October 2, 2025 144

144

144 0002035890 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Leaver Andrew Officer Director Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 749 32290.14 11545354 10/02/2025 NASDAQ Common 10/01/2025 Restricted Stock Vesting Issuer N 749 10/01/2025 Compensation N Andrew J. Leaver 3 Orchard Place London X0 SW1H 0BF

October 2, 2025 144

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144 0001967211 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Willcocks Patrick Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1336 57596.30 11545354 10/02/2025 NASDAQ Common 10/01/2025 Restricted Stock Vesting Issuer N 1336 10/01/2025 Compensation N Patrick Willcocks 3 Orchard Place London X0 SW1H 0BF C

October 2, 2025 144

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144 0001967201 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Pointon Nicholas Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 1327 57208.30 11545354 10/02/2025 NASDAQ Common 10/01/2025 Restricted Stock Vesting Issuer N 1327 10/01/2025 Compensation N Nicholas Pointon 3 Orchard Place London X0 SW1H 0BF Com

October 2, 2025 144

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144 0001967066 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Shiu Daniel Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 811 34963.02 11545354 10/02/2025 NASDAQ Common 10/01/2025 Restricted Stock Vesting Issuer N 811 10/01/2025 Compensation N Daniel Shiu 3 Orchard Place London X0 SW1H 0BF Common 07/02/20

September 19, 2025 EFFECT

EFFECT

X0101 EFFECT 33 LIVE 2025-09-19 16:00:00 F-3 0001859690 Arqit Quantum Inc. 333-289939

September 19, 2025 424B3

ARQIT QUANTUM INC. 11,514,816 Ordinary Shares Offered by Selling Securityholders 5,440,000 Ordinary Shares Underlying Warrants

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(3)  Registration No. 333-289939 PROSPECTUS ARQIT QUANTUM INC. 11,514,816 Ordinary Shares Offered by Selling Securityholders 5,440,000 Ordinary Shares Underlying Warrants This prospectus relates to the offer and sale from time to time by the selling securityholders named in this prospectus (the “Selling Securityholders”) of up to 11,514,816 of our or

September 17, 2025 CORRESP

[Signature page follows]

September 17, 2025 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Technology 100 F Street, NE Washington, D.

September 15, 2025 6-K

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 September 2025 Commission File Number: 001-

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 September 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal

September 15, 2025 F-3/A

As filed with the Securities and Exchange Commission on September 15, 2025

As filed with the Securities and Exchange Commission on September 15, 2025 Registration Statement No.

September 15, 2025 424B5

Arqit Quantum Inc. 48,561 Ordinary Shares

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration Statement No. 333-284343 PROSPECTUS SUPPLEMENT (To Prospectus dated January 29, 2025) Arqit Quantum Inc. 48,561 Ordinary Shares We are offering pursuant to this prospectus supplement and the accompanying prospectus up to an aggregate of 48,561 of our ordinary shares, $0.0025 par value each (the “Ordinary Shares”) in satisfaction of

September 11, 2025 6-K

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 September 2025 Commission File Number: 001-

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 September 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal

September 9, 2025 LETTER

LETTER

September 9, 2025 Nick Pointon Chief Financial Officer Arqit Quantum Inc. 1st Floor, 3 Orchard Place London SW1H 0BF United Kingdom Re: Arqit Quantum Inc. Registration Statement on Form F-3 Filed August 29, 2025 File No. 333-289939 Dear Nick Pointon: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding requests

September 3, 2025 144

144

144 0001967066 XXXXXXXX LIVE 0001859690 Arqit Quantum Inc. 001-40777 3 ORCHARD PLACE LONDON X0 SW1H 0BF 44 203 91 70155 Shiu Daniel Officer Common Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917 3 84.99 11545354 09/03/2025 NASDAQ Common 09/03/2025 Option Granted - 01/04/2021 Issuer N 3 09/03/2025 Cash N Daniel Shiu 3 Orchard Place London X0 SW1H 0BF Common 06/23/2025 6500 2471

August 29, 2025 F-3

As filed with the Securities and Exchange Commission on August 29, 2025

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on August 29, 2025 Registration Statement No.

August 29, 2025 EX-FILING FEES

Security Type

Calculation of Filing Fee Tables F-3 Arqit Quantum Inc. Table 1: Newly Registered and Carry Forward Securities ☐Not Applicable Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee Carry Forward Form Type Carry Forward File Number Carry Forward Initial

August 28, 2025 6-K

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 August 2025 Commission File Number: 001-407

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 August 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London SW1H 0BF, United Kingdom (Address of pr

August 28, 2025 EX-99.2

Form of Proxy Card

Exhibit 99.2 Form of Proxy Card Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. V77646-P36945 For Against Abstain ! ! ! ! ! ! ARQIT QUANTUM INC. Nominees: 1. Election of Directors The Board of D

August 28, 2025 EX-99.1

Arqit Quantum Inc. 1st Floor, 3 Orchard Place London SW1H 0BF United Kingdom

Exhibit 99.1 Arqit Quantum Inc. 1st Floor, 3 Orchard Place London SW1H 0BF United Kingdom August 27, 2025 Dear Shareholder: You are invited to attend the Annual General Meeting of Arqit Quantum Inc. (“Arqit”), which will be held at 2.00 p.m., British Summer Time on September 11, 2025, at 5 Old Broad Street, London, EC2N 1DW United Kingdom and via webcast. Information concerning the matters to be c

May 22, 2025 EX-99.3

Results of Operations of Arqit Quantum Inc., (“Arqit” or the “Company”)

Exhibit 99.3 Results of Operations of Arqit Quantum Inc., (“Arqit” or the “Company”) Comparison of the Six Months Ended March 31, 2025 and 2024 Revenue Revenue decreased by $52 thousand from $119 thousand for the six months ended March 31, 2024 to $67 thousand for the six months ended March 31, 2025. The decrease was due to less revenue being recognized under customer contracts as Arqit continues

May 22, 2025 EX-99.1

Arqit Quantum Inc.

Exhibit 99.1 Arqit Quantum Inc. Announces Financial Results for First Half of Fiscal Year 2025 London, UK – 22 May 2025 Arqit Quantum Inc. (Nasdaq: ARQQ) (“Arqit” or the “Company”), a global leader in quantum-safe encryption, announces financial results for the first half of fiscal year 2025. ●Consistent with management’s preliminary assessment of the expected range of revenue which was announced

May 22, 2025 6-K

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 2025 Commission File Number: 001-40777

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 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of princ

May 22, 2025 EX-99.2

Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements For the period ended 31 March 2025

Table of Contents Exhibit 99.2 Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements For the period ended 31 March 2025 Table of Contents Arqit Quantum Inc. Unaudited Condensed Consolidated Financial Statements as of and for the period ended 31 March 2025 Contents Page Condensed Consolidated Statement of Comprehensive Income (unaudited) 3 Condensed Consolidated Statement

May 22, 2025 424B3

Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 PROSPECTUS SUPPLEMENT (To Prospectus dated November 22, 2022) Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated November 22, 2022 (the “Prospectus”) cove

April 4, 2025 6-K

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 April 2025 Commission File Number: 001-4077

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 April 2025 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of pri

April 4, 2025 EX-99.1

Arqit Quantum Inc.

Exhibit 99.1 Arqit Quantum Inc. Announces Select Preliminary Financial Results for First Half of Fiscal Year 2025 London, UK – 4 April 2025 Arqit Quantum Inc. (“Arqit”), a global leader in quantum-safe encryption, announces select preliminary financial results for the first half of fiscal year 2025. Based on preliminary unaudited results, management expects the Company to report for the first half

February 5, 2025 EX-99.1

ARQIT QUANTUM INC. 2021 INCENTIVE AWARD PLAN (as amended on February 4, 2025)

Exhibit 99.1 ARQIT QUANTUM INC. 2021 INCENTIVE AWARD PLAN (as amended on February 4, 2025) 1.              Establishment of the Plan; Effective Date; Duration. (a)            Establishment of the Plan; Effective Date. Arqit Quantum Inc., a Cayman Islands corporation (the “Company”), hereby establishes this incentive compensation plan to be known as the “Arqit Quantum Inc. 2021 Incentive Award Plan

February 5, 2025 S-8

As filed with the United States Securities and Exchange Commission on February 5, 2025 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ARQIT QUANTUM INC. (Exact

Registration No. 333- As filed with the United States Securities and Exchange Commission on February 5, 2025 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ARQIT QUANTUM INC. (Exact name of Registrant as specified in its charter) Cayman Islands Not Applicable (State or other jurisdiction of incorporation or o

February 5, 2025 EX-FILING FEES

Calculation of Filing Fee Tables Form S-8 (Form Type) Arqit Quantum Inc. (Exact Name of Registrant as Specified in its Charter) Table 1: Newly Registered Securities

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Arqit Quantum Inc.

January 29, 2025 424B5

Arqit Quantum Inc Up to $75,000,000 Ordinary Shares

TABLE OF CONTENTS  Filed pursuant to Rule 424(b)(5)  Registration No. 333-284343 PROSPECTUS SUPPLEMENT (To Prospectus dated January 29, 2025) Arqit Quantum Inc Up to $75,000,000 Ordinary Shares We have entered into an At The Market Offering Agreement, dated January 17, 2025 (the “sales agreement”), with H.C. Wainwright & Co., LLC (the “sales agent” or “Wainwright”), relating to ordinary shares, no

January 28, 2025 CORRESP

[Signature page follows]

January 28, 2025 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Technology 100 F Street, NE Washington, D.

January 27, 2025 LETTER

LETTER

January 27, 2025 Andrew Leaver Chief Executive Officer Arqit Quantum Inc. 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom Re: Arqit Quantum Inc. Registration Statement on Form F-3 Filed January 17, 2025 File No. 333-284343 Dear Andrew Leaver: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding reque

January 17, 2025 EX-3.1

Filed: 20-Dec-2024 15:01 EST Auth Code: D68853963008

Exhibit 3.1 Registrar of Companies Government Administration Building 133 Elgin Avenue George Town Grand Cayman Arqit Quantum Inc. (ROC #374857) (the "Company") TAKE NOTICE that at a general meeting of the Company dated 18 December 2024, the following resolution was passed: 1 Proposal No. 1 – Increase in Authorised Share Capital RESOLVED, as an ordinary resolution, that the authorized share capita

January 17, 2025 F-3

As filed with the Securities and Exchange Commission on January 17, 2025

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on January 17, 2025 Registration No.

January 17, 2025 EX-4.2

ARQIT QUANTUM INC., as issuer as trustee Dated as of [●], [●] TABLE OF CONTENTS

Exhibit 4.2 FORM OF INDENTURE ARQIT QUANTUM INC., as issuer and [●], as trustee INDENTURE Dated as of [●], [●] TABLE OF CONTENTS ARTICLE I DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.01 Definitions 1 Section 1.02 Other Definitions 4 Section 1.03 Incorporation by Reference of Trust Indenture Act 4 Section 1.04 Rules of Construction 4 ARTICLE II THE SECURITIES 5 Section 2.01 Issuable in S

January 17, 2025 EX-1.2

AT THE MARKET OFFERING AGREEMENT January 17, 2025

Exhibit 1.2 AT THE MARKET OFFERING AGREEMENT January 17, 2025 H.C. Wainwright & Co., LLC 430 Park Avenue New York, NY 10022 Ladies and Gentlemen: Arqit Quantum Inc., a Cayman Islands corporation (the “Company”), confirms its agreement (this “Agreement”) with H.C. Wainwright & Co., LLC (the “Manager”) as follows: 1.             Definitions. The terms that follow, when used in this Agreement and any

January 17, 2025 EX-FILING FEES

Calculation of Filing Fee Tables Form F-3 (Form Type) Arqit Quantum Inc. (Exact Name of Registrant as Specified in its Charter) Table 1: Newly Registered Securities and Carry Forward Securities

Exhibit 107 Calculation of Filing Fee Tables Form F-3 (Form Type) Arqit Quantum Inc.

December 19, 2024 6-K

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 December 2024 Commission File Number: 001-4

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 December 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal e

December 13, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / D2BW Ltd - FORM Activist Investment

SC 13D/A 1 arqittt.txt FORM UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 7) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U127 (CUSIP Number) D2BW Limited c/o Arqit Limited 3 Orchard Place London SW1H 0BF, United Kingdom +44 203 91 70155 (Name, Address and Tele

December 10, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / D2BW Ltd - FORM Activist Investment

SC 13D/A 1 arqitt.txt FORM UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 6) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U127 (CUSIP Number) D2BW Limited c/o Arqit Limited 3 Orchard Place London SW1H 0BF, United Kingdom +44 203 91 70155 (Name, Address and Telep

December 9, 2024 EX-99.2

Proxy Card (ARQQ EGM 2024)

Exhibit 99.2 Proxy Card (ARQQ EGM 2024) VOTE BY INTERNET - www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information. Vote by 11:59 P.M. ET on December 17, 2024. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruct

December 9, 2024 6-K

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 December 2024 Commission File Number: 001-4

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 December 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of

December 9, 2024 EX-99.1

Arqit Quantum Inc. 1st Floor, 3 Orchard Place, London, SW1H 0BF United Kingdom

Exhibit 99.1 Arqit Quantum Inc. 1st Floor, 3 Orchard Place, London, SW1H 0BF United Kingdom December 4, 2024 Dear Shareholder: You are invited to attend the Extraordinary General Meeting of Arqit Quantum Inc., which will be held at 2:00 p.m., Greenwich mean Time on Wednesday, December 18, 2024, at 1st Floor, 3 Orchard Place, London, SW1H 0BF United Kingdom and via webcast. Information concerning t

December 5, 2024 EX-19.1

Arqit Quantum Inc. INSIDER TRADING POLICY

Exhibit 19.1 Arqit Quantum Inc. INSIDER TRADING POLICY This document sets forth the Insider Trading Policy (the “Policy”) of Arqit Quantum Inc. and its direct and indirect subsidiaries (collectively, “Arqit”). The Policy establishes the policies and procedures that govern trading by Arqit personnel in Arqit securities. The securities of any other company about which such personnel learns material,

December 5, 2024 EX-13.2

Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Exhibit 13.2 Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2024 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Nick Pointon, Chief Financial Officer of the Company, certify,

December 5, 2024 EX-2.1

ARQIT QUANTUM INC.

Exhibit 2.1 ARQIT QUANTUM INC. Number Ordinary Shares 00[ ] -[ ]- Incorporated under the laws of the Cayman Islands Share capital is US$50,000 divided into 18,760,000 ordinary shares of a par value of US$0.0025 per share and 1,240,000 preference shares of a par value of US$0.0025 per share THIS IS TO CERTIFY THAT [INSERT NAME] is the registered holder of [INSERT NUMBER] Ordinary Shares in the abov

December 5, 2024 EX-4.2

ARQIT QUANTUM INC. AMENDED AND RESTATED 2021 INCENTIVE AWARD PLAN

Exhibit 4.2 ARQIT QUANTUM INC. AMENDED AND RESTATED 2021 INCENTIVE AWARD PLAN 1.Establishment of the Plan; Effective Date; Duration. (a)Establishment of the Plan; Effective Date. Arqit Quantum Inc., a Cayman Islands corporation (the “Company”), hereby establishes this incentive compensation plan to be known as the “Arqit Quantum Inc. 2021 Incentive Award Plan,” as amended from time to time (the “P

December 5, 2024 EX-13.1

Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Exhibit 13.1 Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2024 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Andy Leaver, Chief Executive Officer of the Company, certify, p

December 5, 2024 EX-12.1

Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

Exhibit 12.1 Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Andy Leaver, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light

December 5, 2024 20-F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EX

December 5, 2024 6-K

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 December 2024 Commission File Number: 001-4

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 December 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of

December 5, 2024 EX-2.10

DESCRIPTION OF SECURITIES

Exhibit 2.10 DESCRIPTION OF SECURITIES The following description of the material terms of the securities of Arqit Quantum Inc. includes a summary of specified provisions of the Memorandum and Articles of association of the Company (the “Articles) and the forms of the warrants described herein. This description is subject to and qualified in its entirety by reference to the Articles and the forms o

December 5, 2024 EX-12.2

Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

Exhibit 12.2 Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Nick Pointon, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light

December 5, 2024 EX-99.1

Arqit Quantum Inc. Announces Financial and Operational Results for the Fiscal Year 2024 $293,000 in revenue generated for the full fiscal year Signed seven figure multi-year SKA-PlatformTM enterprise license contract Commence fiscal year 2025 with an

Exhibit 99.1 Arqit Quantum Inc. Announces Financial and Operational Results for the Fiscal Year 2024 $293,000 in revenue generated for the full fiscal year Signed seven figure multi-year SKA-PlatformTM enterprise license contract Commence fiscal year 2025 with annual recurring revenue backlog Cash position of $18.7 million at the end of the period London, UK – 5 December 2024 – Arqit Quantum Inc.

December 5, 2024 EX-15.1

Consent of Independent Registered Public Accounting Firm

Exhibit 15.1 Consent of Independent Registered Public Accounting Firm We hereby consent to the incorporation by reference in the following Arqit Quantum Inc. registration statements: (1)registration statement on Form S-8 (File No. 333-262215); (2)registration statement on Form S-8 (File No. 333-275960); (3)registration statement on Form F-3 (File No. 333-268786); and (4)registration statement on F

December 5, 2024 EX-1.1

www.verify.gov.ky File#: 374857

Exhibit 1.1 Registrar of Companies Government Administration Building 133 Elgin Avenue George Town Grand Cayman Arqit Quantum Inc. (ROC #374857) (the “Company”) TAKE NOTICE that at a general meeting of the shareholders of the Company dated 18 September 2024, the following resolutions were passed: RESOLVED, as an ordinary resolution, that, subject to the average closing price, rounded to the neares

December 3, 2024 424B3

Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 PROSPECTUS SUPPLEMENT (To Prospectus dated November 22, 2022) Arqit Quantum Inc. 4,717,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 595,666 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated November 22, 2022 (the “Prospectus”) cove

December 3, 2024 6-K

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 December 2024 Commission File Number: 001-4

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 December 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 Orchard Place London, SW1H 0BF United Kingdom (Address of

November 14, 2024 SC 13G/A

ARQQ / Arqit Quantum Inc. / Williams Sarah Jane - SC 13G/A Passive Investment

SC 13G/A 1 arqitsc13ga1.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Act of 1934 (Amendment No. 1)* ARQIT QUANTUM INC. (Name of Issuer) Ordinary Shares, par value $0.000004 per share (Title of Class of Securities) G0567U 127 (CUSIP Number) October 9, 2024 (Date of Event Which Requires Filing of this Statement) Check the appr

October 11, 2024 6-K

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 October 2024 Commission File Number: 001-40

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 October 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal ex

October 2, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / Heritage Assets SCSp. - SC 13D/A Activist Investment

UNITED STATES SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 3)* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares, $0.000004 par value per share (Title of Class of Securities) G0567U127 (CUSIP Number) Heritage Assets SCSp c/o Heritage Services SAM, 7 rue du Gabian, 98000 Monaco Attention: Cristina Levis +377 97 97 63

October 2, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / D2BW Ltd - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 5) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U127 (CUSIP Number) D2BW Limited c/o Arqit Limited 3 Orchard Place London SW1H 0BF, United Kingdom +44 203 91 70155 (Name, Address and Telephone Number of Person Autho

October 1, 2024 424B5

Arqit Quantum Inc. 5,440,000 Ordinary Shares

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration Statement No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. 5,440,000 Ordinary Shares We are offering to certain investors pursuant to this prospectus supplement and the accompanying base prospectus up to an aggregate of 5,440,000 of our ordinary shares, $0.000004 par value each (the “Or

October 1, 2024 EX-10.1

SECURITIES PURCHASE AGREEMENT

Exhibit 10.1 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of September 30, 2024, between Arqit Quantum Inc., a Cayman Islands exempted company (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively the “Purchasers”). WHEREAS, subject to the terms and

October 1, 2024 EX-99.1

Arqit Quantum Inc. Announces $13.6 Million Registered Direct Offering

Exhibit 99.1 Arqit Quantum Inc. Announces $13.6 Million Registered Direct Offering London, UK – 30 September 2024 – Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (“Arqit” or the “Company”), a global leader in quantum encryption technology, today announced that it has entered into a definitive securities purchase agreement with existing shareholders Heritage Assets SCSP, Notion Capital, Carlo Calabria,

October 1, 2024 6-K

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 October 2024 Commission File Number: 001-40

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 October 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal ex

October 1, 2024 SC 13G

ARQQ / Arqit Quantum Inc. / Williams Sarah Jane - SC 13G Passive Investment

SC 13G 1 arqitsc13g.htm SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Act of 1934 (Amendment No. )* ARQIT QUANTUM INC. (Name of Issuer) Ordinary Shares, par value $0.000004 per share (Title of Class of Securities) G0567U 127 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of this Statement) Check the appropri

October 1, 2024 EX-4.1

ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc.

Exhibit 4.1 THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE U.S. SECURITIES ACT OF 1933, AS AMENDED (“SECURITIES ACT”), OR THE SECURITIES LAWS OF ANY STATE OR OTHER JURISDICTION, AND MAY NOT BE SOLD, TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR SUCH LAWS OR AN EXEMPTION FROM REGISTRATION UNDER

October 1, 2024 424B3

Arqit Quantum Inc.

Filed Pursuant to Rule 424(b)(3) Registration No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. This prospectus supplement supplements and amends the prospectus dated December 30, 2022 (the “Prospectus”), as supplemented and amended by that certain prospectus supplement dated December 30, 2022, that certain prospectus supplement dated September 8, 2023

September 27, 2024 EX-99.1

Arqit announces leadership transition with the appointment of a new Chief Executive Officer

Exhibit 99.1 Arqit announces leadership transition with the appointment of a new Chief Executive Officer London, UK – 21:30 BST 27 September 2024 – Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW), a leading provider of quantum-safe encryption, today announced a leadership transition. Andy Leaver, a seasoned software company executive and Operating Partner from Notion Capital, has been appointed as Chief

September 27, 2024 6-K

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 September 2024 Commission File Number: 001-

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 September 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal

September 19, 2024 EX-99.1

Arqit Quantum Inc. Announces 25:1 Reverse Share Split

Exhibit 99.1 Arqit Quantum Inc. Announces 25:1 Reverse Share Split LONDON, UK September 19, 2024 /Globenewswire/ - Arqit Quantum Inc. (Nasdaq: ARQQ) (“Arqit” or the “Company”), a leader in quantum safe encryption, today announces that, following approval by the Company’s shareholders at its annual general meeting held on September 18, 2024, the Company’s Board of Directors has determined to effect

September 19, 2024 6-K

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 September 2024 Commission File Number: 001-

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 September 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal

September 16, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / D2BW Ltd - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 4) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U101 (CUSIP Number) D2BW Limited c/o Arqit Limited 3 Orchard Place London SW1H 0BF, United Kingdom +44 203 91 70155 (Name, Address and Telephone Number of Person Autho

August 27, 2024 EX-99.1

Arqit Quantum Inc. 3 Orchard Place London SW1H 0BF, United Kingdom

Exhibit 99.1 Arqit Quantum Inc. 3 Orchard Place London SW1H 0BF, United Kingdom August 27, 2024 Dear Shareholder: You are invited to attend the Annual General Meeting of Arqit Quantum Inc. (“Arqit”), which will be held at 3:00 p.m., British Summer Time on September 18, 2024, at 5 Old Broad Street, London, EC2N 1DW United Kingdom and via webcast. Information concerning the matters to be considered

August 27, 2024 6-K

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 August 2024 Commission File Number: 001-407

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 August 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 3 Orchard Place London SW1H 0BF, United Kingdom (Address of principal exe

August 27, 2024 EX-99.2

Important Notice Regarding the Availability of Proxy Materials for the General Meeting: The Notice and Proxy Statement is available at www.proxyvote.com. V56362-P17990 ARQIT QUANTUM INC. General Meeting of Shareholders September 18, 2024 3:00 PM (BST

Exhibit 99.2 Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. V56361-P17990 1b. MANFREDI LEFEBVRE D’OVIDIO Nominees: 1a. DAVID WILLIAMS 1c. GARTH RITCHIE from US$50,000 divided into 469,000,001 o

May 20, 2024 424B3

Arqit Quantum Inc. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 PROSPECTUS SUPPLEMENT (To Prospectus dated November 22, 2022) Arqit Quantum Inc. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated November 22, 2022 (the “Prospectus”)

May 20, 2024 EX-99.3

Results of Operations

Exhibit 99.3 Results of Operations Comparison of the Six Months Ended March 31, 2024 and 2023 Revenue Revenue increased by $100 thousand from $19 thousand for the six months ended March 31, 2023 to $119 thousand for the six months ended March 31, 2024. The increase was due to increased sales volumes compared to the six months ended March 31, 2023 as a result of new channel partnerships formed in t

May 20, 2024 6-K

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 2024 Commission File Number: 001-40777

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 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom (Ad

May 20, 2024 EX-99.1

Arqit Quantum Inc. Announces Financial and Operational Results for the First Half of Fiscal Year 2024 $119,000 of revenue for the six month period ended 31 March 2024 with certain prospective deals slipping to the second half of the fiscal year Renew

Exhibit 99.1 Arqit Quantum Inc. Announces Financial and Operational Results for the First Half of Fiscal Year 2024 $119,000 of revenue for the six month period ended 31 March 2024 with certain prospective deals slipping to the second half of the fiscal year Renewal or contract extension with nine existing customers, representing revenue from small engagements with potential for larger reveneue opp

May 20, 2024 EX-99.1

Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements For the period ended 31 March 2024

Table of Contents Exhibit 99.2 Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements For the period ended 31 March 2024 Table of Contents Arqit Quantum Inc. Unaudited Condensed Consolidated Financial Statements as of and for the period ended 31 March 2024 Contents Page Condensed Consolidated Statement of Comprehensive Income (unaudited) 3 Condensed Consolidated Statement

April 15, 2024 424B3

Arqit Quantum Inc.

Filed Pursuant to Rule 424(b)(3) Registration No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. This prospectus supplement supplements and amends the prospectus dated December 30, 2022 (the “Prospectus”), as supplemented and amended by that certain prospectus supplement dated December 30, 2022 and that certain prospectus supplement dated September 8, 2

April 15, 2024 EX-10.1

SECURITIES PURCHASE AGREEMENT

Exhibit 10.1 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of March 29, 2024, between Arqit Quantum Inc., a Cayman Islands exempted company (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively the “Purchasers”). WHEREAS, subject to the terms and cond

April 15, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / D2BW Ltd - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 3) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U101 (CUSIP Number) D2BW Limited c/o Arqit Limited Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom +44 203 91 70155 (Name, Address and Telepho

April 15, 2024 424B5

Arqit Quantum Inc. 1,241,379 Ordinary Shares

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration Statement No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. 1,241,379 Ordinary Shares Pursuant to this prospectus supplement and the accompanying prospectus, we are offering to D2BW Limited, an existing shareholder beneficially owned by our Chief Executive Officer, David Williams, and ou

April 15, 2024 6-K

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 April 2024 Commission File Number: 001-4077

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 April 2024 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom (

February 13, 2024 SC 13D/A

ARQQ / Arqit Quantum Inc. / Evolution Technology Fund II, SCSP. - SC 13D/A Activist Investment

SC 13D/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-l(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a) (Amendment No. 1)* Arqit Quantum Inc. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) G0567U101 (CUSIP Number) The Evolut

January 26, 2024 SC 13G

ARQQ / Arqit Quantum Inc. / NOTION CAPITAL III GP LLP - SC 13G Passive Investment

SC 13G 1 d733953dsc13g.htm SC 13G SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares (Title of Class of Securities) G0567U101 (CUSIP Number) (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this

December 8, 2023 EX-99.1

ARQIT QUANTUM INC. 2021 INCENTIVE AWARD PLAN (as amended on October 12, 2023)

Exhibit 99.1 ARQIT QUANTUM INC. 2021 INCENTIVE AWARD PLAN (as amended on October 12, 2023) 1. Establishment of the Plan; Effective Date; Duration. (a) Establishment of the Plan; Effective Date. Arqit Quantum Inc., a Cayman Islands corporation (the “Company”), hereby establishes this incentive compensation plan to be known as the “Arqit Quantum Inc. 2021 Incentive Award Plan,” as amended from time

December 8, 2023 EX-FILING FEES

Calculation of Filing Fee Tables Form S-8 (Form Type) Arqit Quantum Inc. (Exact Name of Registrant as Specified in its Charter) Table 1: Newly Registered Securities

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) Arqit Quantum Inc.

December 8, 2023 S-8

As filed with the United States Securities and Exchange Commission on December 8, 2023 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ARQIT QUANTUM INC. (Exact

Registration No. 333- As filed with the United States Securities and Exchange Commission on December 8, 2023 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ARQIT QUANTUM INC. (Exact name of Registrant as specified in its charter) Cayman Islands Not Applicable (State or other jurisdiction of incorporation or o

November 21, 2023 20-F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EX

November 21, 2023 EX-12.1

Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

Exhibit 12.1 Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, David Williams, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in lig

November 21, 2023 EX-97.1

ARQIT QUANTUM INC. POLICY FOR THE RECOVERY OF ERRONEOUSLY AWARDED COMPENSATION

Exhibit 97.1 ARQIT QUANTUM INC. POLICY FOR THE RECOVERY OF ERRONEOUSLY AWARDED COMPENSATION A. OVERVIEW In accordance with the applicable rules of The Nasdaq Stock Market (the “Nasdaq Rules”), Section 10D and Rule 10D-1 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) (“Rule 10D-1”), the Board of Directors (the “Board”) of Arqit Quantum Inc. (the “Company”) has adopted this

November 21, 2023 EX-2.9

DESCRIPTION OF SECURITIES

Exhibit 2.9 DESCRIPTION OF SECURITIES The following description of the material terms of the securities of Arqit Quantum Inc. includes a summary of specified provisions of the Memorandum and Articles of association of the Company (the “Articles) and the forms of the warrants described herein. This description is subject to and qualified in its entirety by reference to the Articles and the forms of

November 21, 2023 EX-13.2

Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Exhibit 13.2 Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2023 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Nick Pointon, Chief Financial Officer of the Company, certify,

November 21, 2023 6-K

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 November 2023 Commission File Number: 001-4

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 November 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdo

November 21, 2023 EX-12.2

Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

Exhibit 12.2 Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Nick Pointon, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light

November 21, 2023 EX-99.1

Arqit Quantum Inc. Announces Financial and Operational Results for the Fiscal Year 2023 $5.6 million of revenue and other operating income from discontinued operations for fiscal year 2023 Revenue for the second half of fiscal year 2023 from the sale

Exhibit 99.1 Arqit Quantum Inc. Announces Financial and Operational Results for the Fiscal Year 2023 $5.6 million of revenue and other operating income from discontinued operations for fiscal year 2023 Revenue for the second half of fiscal year 2023 from the sale of QuantumCloud™ symmetric key agreement encryption technology increased from the first half of fiscal year 2023 New specialised applica

November 21, 2023 EX-15.1

Consent of Independent Registered Public Accounting Firm

Exhibit 15.1 Consent of Independent Registered Public Accounting Firm We hereby consent to the incorporation by reference in the following Arqit Quantum Inc. registration statements: (1)registration statement on Form S-8 (File No. 333-262215); (2)registration statement on Form F-3 (File No. 333-268786); and (3)registration statement on Form F-3 (File No. 333-259982) of our report dated November 21

November 21, 2023 EX-13.1

Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Exhibit 13.1 Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2023 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, David Williams, Chief Executive Officer of the Company, certify

October 23, 2023 6-K

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 October 2023 Commission File Number: 001-40

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 October 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom

September 15, 2023 SC 13D/A

ARQQ / Arqit Quantum Inc / Heritage Assets SCSp. - SC 13D/A Activist Investment

SC 13D/A 1 tm2326263d1sc13da.htm SC 13D/A UNITED STATES SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 2)* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares, $0.0001 par value per share (Title of Class of Securities) G0567U101 (CUSIP Number) Heritage Assets SCSp c/o Heritage Services SAM 7 rue du Gabian - 98000 Monaco

September 11, 2023 EX-4.2

PLACEMENT AGENT ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc.

Exhibit 4.2 PLACEMENT AGENT ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc. Warrant Shares: Initial Exercise Date: September 12, 2023 THIS PLACEMENT AGENT ORDINARY SHARE PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on

September 11, 2023 EX-99.1

Arqit Quantum Inc. Announces $16.2 Million Registered Direct Offering

Exhibit 99.1 Arqit Quantum Inc. Announces $16.2 Million Registered Direct Offering London, UK – 8 September 2023 – Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (“Arqit” or the “Company”), a global leader in quantum encryption technology, today announced that it has entered into a definitive securities purchase agreement for the sale and purchase of 12,820,513 of the Company’s ordinary shares, $0.0001

September 11, 2023 EX-10.1

SECURITIES PURCHASE AGREEMENT

Exhibit 10.1 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of September 8, 2023, between Arqit Quantum Inc., a Cayman Islands exempted company (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively the “Purchasers”). WHEREAS, subject to the terms and c

September 11, 2023 424B5

Arqit Quantum Inc. 20,755,677 Ordinary Shares Warrants to Purchase up to 20,755,677 Ordinary Shares Placement Agent Warrants to Purchase up to 705,128 Ordinary Shares (and the Ordinary Shares underlying the Warrants and Placement Agent Warrants)

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration Statement No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. 20,755,677 Ordinary Shares Warrants to Purchase up to 20,755,677 Ordinary Shares Placement Agent Warrants to Purchase up to 705,128 Ordinary Shares (and the Ordinary Shares underlying the Warrants and Placement Agent Warrants) W

September 11, 2023 EX-4.1

ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc.

Exhibit 4.1 ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc. Warrant Shares: Initial Exercise Date: September 12, 2023    THIS ORDINARY SHARE PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date hereof (the

September 11, 2023 6-K

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 September 2023 Commission File Number: 001-

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 September 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingd

September 8, 2023 424B3

Arqit Quantum Inc.

Filed Pursuant to Rule 424(b)(3) Registration No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. This prospectus supplement supplements and amends the prospectus dated December 30, 2022 (the “Prospectus”), as supplemented and amended by that certain prospectus supplement dated December 30, 2022 covering the offering, issuance and sale of up to a maximum

September 7, 2023 EX-99.1

-ends-

Exhibit 99.1 New Product Launch and Business Update London, UK - 7 September 2023 - Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (Arqit), a leader in quantum-safe encryption, today announced the launch of its third application product, Arqit WalletSecure™. Arqit sells a core Symmetric Key Agreement Platform-as-a-Service which can be used for any encryption task. This announcement follows the launch of

September 7, 2023 6-K

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 September 2023 Commission File Number: 001-

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 September 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingd

September 7, 2023 6-K

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 September 2023 Commission File Number: 001-

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 September 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingd

August 8, 2023 6-K

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 August 2023 Commission File Number: 001-407

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 August 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom

August 8, 2023 EX-99.2

THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) D

Exhibit 99.2 THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date SCAN TO VIEW MATERIALS & VOTE 0 0 0 0 0 0 00006180171 R1.0.0.6 ARQIT QUANTUM INC. 7TH FLOOR, NOVA NORTH 11 BRESSENDEN PLACE LONDON EN

August 8, 2023 EX-99.1

Arqit Quantum Inc. Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY United Kingdom

Exhibit 99.1 Arqit Quantum Inc. Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY United Kingdom August 8, 2023 Dear Shareholder: You are invited to attend the Annual General Meeting of Arqit Quantum Inc., which will be held at 3:00 p.m., British Summer Time on Thursday, September 7, 2023, at Nova North, Floor 7, 11 Bressenden Place, London, SW1E 5BY United Kingdom and via webcast. Informat

June 2, 2023 EX-99.2

Arqit Quantum Inc. (“Arqit”) Management’s Discussion and Analysis of Financial Condition and Results of Operations

Exhibit 99.2 Arqit Quantum Inc. (“Arqit”) Management’s Discussion and Analysis of Financial Condition and Results of Operations Comparison of the Six Months Ended March 31, 2023 and 2022 Revenue Revenue decreased by $5.3 million from $5.3 million for the six months ended March 31, 2022 to $19 thousand for the six months ended March 31, 2023. The decrease was due to the time required to establish r

June 2, 2023 EX-99.1

Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements As of and for the period ended 31 March 2023

Exhibit 99.1 Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements As of and for the period ended 31 March 2023 Arqit Quantum Inc. Unaudited Condensed Consolidated Interim Financial Statements as of and for the period ended 31 March 2023 Contents Page Condensed Consolidated Statement of Comprehensive Income (unaudited) 2 Condensed Consolidated Statement of Financial Posi

June 2, 2023 6-K

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 June 2023 Commission File Number: 001-40777

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 June 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom (A

May 17, 2023 424B3

Arqit Quantum Inc. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 PROSPECTUS SUPPLEMENT (To Prospectus dated November 22, 2022) Arqit Quantum Inc. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated November 22, 2022 (the “Prospectus”)

May 17, 2023 6-K

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 2023 Commission File Number: 001-40777

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 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom (Ad

May 17, 2023 EX-99.1

Arqit Quantum Inc. Announces Financial and Operational Results for the First Half of Fiscal Year 2023 $2.6 million of revenue and other operating income for the six month period First cloud platform revenues generated through previously announced cha

Exhibit 99.1 Arqit Quantum Inc. Announces Financial and Operational Results for the First Half of Fiscal Year 2023 $2.6 million of revenue and other operating income for the six month period First cloud platform revenues generated through previously announced channel partnership Significant cost reduction initiative actioned Adviser retained in connection with potential sale of satellite division

February 21, 2023 6-K

our report on Form 6-K, filed with the SEC on February 21, 2023.

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 February 2023 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdo

February 21, 2023 424B5

Arqit Quantum Inc. 10,000,000 Ordinary Shares Warrants to Purchase up to 7,500,000 Ordinary Shares Placement Agent Warrants to Purchase up to 550,000 Ordinary Shares (and the Ordinary Shares underlying the Warrants and Placement Agent Warrants)

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration Statement No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc. 10,000,000 Ordinary Shares Warrants to Purchase up to 7,500,000 Ordinary Shares Placement Agent Warrants to Purchase up to 550,000 Ordinary Shares (and the Ordinary Shares underlying the Warrants and Placement Agent Warrants) We

February 21, 2023 EX-10.1

Form of Securities Purchase Agreement

Exhibit 10.1 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of February 17, 2023, between Arqit Quantum Inc., a Cayman Islands exempted company (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively the “Purchasers”). WHEREAS, subject to the terms and c

February 21, 2023 EX-4.1

Form of Warrant

Exhibit 4.1 ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc. Warrant Shares: Initial Exercise Date: February 22, 2023           THIS ORDINARY SHARE PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date hereo

February 21, 2023 EX-4.2

Form of Placement Agent Warrant

Exhibit 4.2 PLACEMENT AGENT ORDINARY SHARE PURCHASE WARRANT Arqit Quantum Inc. Warrant Shares: Initial Exercise Date: February 22, 2023 THIS PLACEMENT AGENT ORDINARY SHARE PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on o

February 21, 2023 EX-99.1

Arqit Quantum Inc. Announces $20 Million Registered Direct Offering

Exhibit 99.1 Arqit Quantum Inc. Announces $20 Million Registered Direct Offering London, UK – 17 February 2023 – Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (“Arqit”), a global leader in quantum encryption technology, today announced that it has entered into a definitive securities purchase agreement with several institutional investors (the “Securities Purchase Agreement”) for the sale and purchase

February 3, 2023 SC 13D/A

ARQQ / Arqit Quantum Inc / D2BW Ltd - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 2) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U101 (CUSIP Number) D2BW Limited c/o Arqit Limited Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom +44 203 91 70155 (Name, Address and Telepho

January 6, 2023 SC 13G

ARQQ / Arqit Quantum Inc / NOTION CAPITAL III GP LLP - SC 13G Passive Investment

SC 13G SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares (Title of Class of Securities) G0567U101 (CUSIP Number) January 5, 2023 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this schedule is

December 30, 2022 424B5

Arqit Quantum Inc Up to $50,000,000 Ordinary Shares

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(5)  Registration Statement No. 333-268786 PROSPECTUS SUPPLEMENT (To Prospectus dated December 30, 2022) Arqit Quantum Inc Up to $50,000,000 Ordinary Shares We have entered into an At The Market Offering Agreement, dated December 14, 2022 (the “sales agreement”), with H.C. Wainwright & Co., LLC (the “sales agent” or “Wainwright”), relating to ordinar

December 28, 2022 F-3/A

As filed with the Securities and Exchange Commission on December 28, 2022

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on December 28, 2022 Registration No.

December 28, 2022 CORRESP

[Signature page follows]

December 28, 2022 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Technology 100 F Street, NE Washington, D.

December 23, 2022 LETTER

LETTER

United States securities and exchange commission logo December 23, 2022 Patrick Wilcox General Counsel Arqit Quantum Inc.

December 14, 2022 EX-4.2

Form of Indenture.

EX-4.2 3 tm2232467d2ex4-2.htm EXHIBIT 4.2 Exhibit 4.2 FORM OF INDENTURE ARQIT QUANTUM INC., as issuer and [●], as trustee INDENTURE Dated as of [●], [●] TABLE OF CONTENTS ARTICLE I DEFINITIONS AND INCORPORATION BY REFERENCE 1 Section 1.01 Definitions 1 Section 1.02 Other Definitions 4 Section 1.03 Incorporation by Reference of Trust Indenture Act 4 Section 1.04 Rules of Construction 4 ARTICLE II T

December 14, 2022 EX-1.2

At The Market Offering Agreement, dated December 14, 2022, between the Registrant and H.C. Wainwright & Co., LLC.

EX-1.2 2 tm2232467d2ex1-2.htm EXHIBIT 1.2 Exhibit 1.2 AT THE MARKET OFFERING AGREEMENT December 14, 2022 H.C. Wainwright & Co., LLC 430 Park Avenue New York, NY 10022 Ladies and Gentlemen: Arqit Quantum Inc., a Cayman Islands corporation (the “Company”), confirms its agreement (this “Agreement”) with H.C. Wainwright & Co., LLC (the “Manager”) as follows: 1.             Definitions. The terms that

December 14, 2022 EX-FILING FEES

Calculation of Filing Fee Tables.

Exhibit 107 Calculation of Filing Fee Tables Form F-3 (Form Type) Arqit Quantum Inc.

December 14, 2022 F-3

Form F-3 with the Securities and Exchange Commission, or the SEC, on December

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on December 14, 2022 Registration No.

December 14, 2022 EX-13.2

Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Exhibit 13.2 Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Nick Pointon, Chief Financial Officer of the Company, certify,

December 14, 2022 EX-99.1

Arqit Quantum Inc. Announces Financial and Operational Results for the Fiscal Year 2022 $20 million of revenue and other operating income for the fiscal year Technology innovation expected to have positive impact on future results Recent major channe

Exhibit 99.1 Arqit Quantum Inc. Announces Financial and Operational Results for the Fiscal Year 2022 $20 million of revenue and other operating income for the fiscal year Technology innovation expected to have positive impact on future results Recent major channel partner announcements clarify path to success London, UK – 14 December 2022 – Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (“Arqit”), a glo

December 14, 2022 20-F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended September 30, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EX

December 14, 2022 EX-12.1

Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

Exhibit 12.1 Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, David Williams, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in lig

December 14, 2022 EX-13.1

Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Exhibit 13.1 Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the “Company”) on Form 20-F for the year ended September 30, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, David Williams, Chief Executive Officer of the Company, certify

December 14, 2022 6-K

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 December 2022 Commission File Number: 001-4

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 December 2022 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdo

December 14, 2022 EX-2.5

the description of the securities contained in exhibit 2.5 to the Company’s annual report on Form 20-F filed with the SEC on December 14, 2022.

Exhibit 2.5 DESCRIPTION OF SECURITIES The following description of the material terms of the securities of Arqit Quantum Inc. (the ?Company?) includes a summary of specified provisions of the Memorandum and Articles of association of the Company (the ?Articles). This description is qualified by reference to the Articles. General The Company is a Cayman Islands exempted company (company number 3748

December 14, 2022 EX-12.2

Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

Exhibit 12.2 Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Nick Pointon, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light

November 22, 2022 424B3

ARQIT QUANTUM INC. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants

TABLE OF CONTENTS  Filed Pursuant to Rule 424(b)(3)  Registration No. 333-259982 PROSPECTUS ARQIT QUANTUM INC. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants This prospectus relates to the offer and sale from time to time by the selling securityholders named in this prospectus (the “Selling Securityholders”) of up to 117,92

November 9, 2022 POS AM

As filed with the Securities and Exchange Commission on November 9, 2022

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on November 9, 2022 Registration Statement No.

November 9, 2022 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Table Form F-3 (Form Type) Arqit Quantum Inc.

September 8, 2022 6-K

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 September 2022 Commission File Number: 001-

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 September 2022 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingd

August 15, 2022 LETTER

LETTER

United States securities and exchange commission logo August 15, 2022 Nick Pointon Chief Financial Officer Arqit Quantum Inc.

August 8, 2022 EX-99.2

Form of Proxy Card

Exhibit 99.2 Form of Proxy Card 2011 CRYSTAL DRIVE SUITE 325 ARLINGTON, VA 22202 TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: ? SCAN TO VIEW MATERIALS &VOTE t> VOTE BY INTERNET? www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information. Vote by 11 :59 P.M. ET on 09/06/2022. Have your proxy card in

August 8, 2022 EX-99.1

Arqit Quantum Inc. Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY United Kingdom

Exhibit 99.1 Arqit Quantum Inc. Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY United Kingdom August 8, 2022 Dear Shareholder: You are invited to attend the Annual General Meeting of Arqit Quantum Inc., which will be held at 12:00 p.m., Eastern Time, on Wednesday, September 7, 2022, at 251 18th Street, Arlington, Virginia, USA 22202 and via webcast. Information concerning the matters to

August 8, 2022 6-K

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 August 2022 Commission File Number: 001-407

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 August 2022 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom

July 11, 2022 CORRESP

July 11, 2022

July 11, 2022 Kathryn Jacobson, Senior Staff Accountant Robert Littlepage, Accountant Branch Chief Division of Corporation Finance Office of Technology United States Securities and Exchange Commission Washington, D.

June 28, 2022 LETTER

LETTER

United States securities and exchange commission logo June 28, 2022 Nick Pointon Chief Financial Officer Arqit Quantum Inc.

June 15, 2022 CORRESP

June 15, 2022

June 15, 2022 VIA EDGAR Kathryn Jacobson, Senior Staff Accountant Robert Littlepage, Accountant Branch Chief Division of Corporation Finance Office of Technology United States Securities and Exchange Commission Washington, D.

June 1, 2022 LETTER

LETTER

United States securities and exchange commission logo June 1, 2022 Nick Pointon Chief Financial Officer Arqit Quantum Inc.

May 12, 2022 424B3

Arqit Quantum Inc. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-259982 Supplement No. 1 (To Prospectus dated December 23, 2021) Arqit Quantum Inc. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants This prospectus supplement updates and amends certain information contained in the prospectus dated December 23, 2021 (the ?Prospectus?) cove

May 12, 2022 EX-99.1

Arqit Quantum Inc. Announces Financial and Operational Results for the First Half of Fiscal Year 2022 Generated $12.3 million of revenue and other operating income in the first half of fiscal year 2022

Exhibit 99.1 Arqit Quantum Inc. Announces Financial and Operational Results for the First Half of Fiscal Year 2022 Generated $12.3 million of revenue and other operating income in the first half of fiscal year 2022 London, UK ? 12 May 2022 ? Arqit Quantum Inc. (Nasdaq: ARQQ, ARQQW) (?Arqit?), a global leader in quantum encryption technology, today announced its operational and financial results fo

May 12, 2022 6-K

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 2022 Commission File Number: 001-40777

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 2022 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) Nova North, Floor 7, 11 Bressenden Place London SW1E 5BY, United Kingdom (Ad

May 12, 2022 EX-99.2

Arqit Founders Voluntarily Extend Lock-Up Signals long-term commitment

Exhibit 99.2 Arqit Founders Voluntarily Extend Lock-Up Signals long-term commitment London, UK ? 12 May 2022 ? Arqit Quantum Inc. (the ?Company?) today announces that the majority of former shareholders of Arqit Limited (or their transferees) and former members of Centricus Heritage, LLC, the sponsor of Centricus Acquisition Corp. have voluntarily entered into extensions of their lock-up agreement

January 18, 2022 S-8

As filed with the United States Securities and Exchange Commission on January 18, 2022 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ARQIT QUANTUM INC. (Exact

Registration No. 333- As filed with the United States Securities and Exchange Commission on January 18, 2022 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ARQIT QUANTUM INC. (Exact name of Registrant as specified in its charter) Cayman Islands Not Applicable (State or other jurisdiction of incorporation or o

January 6, 2022 SC 13G

ARQQ / Arqit Quantum Inc / NOTION CAPITAL III GP LLP - SC 13G Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares (Title of Class of Securities) G0567U101 (CUSIP Number) September 3, 2021 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this schedule is file

December 23, 2021 424B3

ARQIT QUANTUM INC. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants

TABLE OF CONTENTS ?Filed Pursuant to Rule 424(b)(3)? ?Registration No. 333-259982? PROSPECTUS ARQIT QUANTUM INC. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants This prospectus relates to the offer and sale from time to time by the selling securityholders named in this prospectus (the ?Selling Securityholders?) of up to 117,

December 16, 2021 6-K

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 December 2021 Commission File Number: 001-4

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 December 2021 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 More London Riverside London SE1 2RE, United Kingdom (Addr

December 16, 2021 EX-4.7

Form of Rollover Option Agreement relating to the grant of an option to acquire shares in Arqit Quantum Inc.

Exhibit 4.7 ? ? ? ? ? ? ? ? ? ? ? ? ? Form of Rollover Option Agreement Relating to the grant of an option to acquire shares in ArQit Quantum Inc. between ArQit Limited ArQit Quantum Inc. and [Name of optionholder (A)] ? Table of Contents ? ? ? ? ? ? ? ? ? Page 1. DEFINITIONS AND INTERPRETATION ? 2 ? 2. ? GRANT OF THE OPTION AND RELEASE ? 4 ? 3. ? NON-ASSIGNABILITY ? 5 ? 4. ? RESTRICTIONS ATTACHIN

December 16, 2021 EX-13.2

Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Exhibit 13.2 Certification by the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the ?Company?) on Form 20-F for the year ended September 30, 2021 as filed with the Securities and Exchange Commission on the date hereof (the ?Report?), I, Nick Pointon, Chief Financial Officer of the Company, certify,

December 16, 2021 EX-12.1

Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

Exhibit 12.1 ? Certification by the Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, David Williams, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in l

December 16, 2021 EX-99.2

December 16, 2021 Arqit Quantum Inc. (NASDAQ: ARQQ) 2021 Fiscal Year Earnings Call Presentation Stronger simpler encryption JM0

Exhibit 99.2 December 16, 2021 Arqit Quantum Inc. (NASDAQ: ARQQ) 2021 Fiscal Year Earnings Call Presentation Stronger simpler encryption JM0 Safe Harbor Statement 2 The statements in this presentation that are not historical facts, including, most importantly, those statements preceded by, or that include, the words ?will,? ?may,? ?believe,? ?projects,? ?expects,? ?anticipates? or the negation the

December 16, 2021 EX-12.2

Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

Exhibit 12.2 ? Certification by the Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, Nick Pointon, certify that: 1. I have reviewed this annual report on Form 20-F of Arqit Quantum Inc.; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in lig

December 16, 2021 20-F

Form 20-F

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☑ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended September 30, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EX

December 16, 2021 EX-13.1

Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Exhibit 13.1 ? Certification by the Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 In connection with the annual report of Arqit Quantum Inc. (the ?Company?) on Form 20-F for the year ended September 30, 2021 as filed with the Securities and Exchange Commission on the date hereof (the ?Report?), I, David Williams, Chief Executive Officer of the Company, certi

December 16, 2021 EX-99.1

Arqit Quantum Inc. announces financial and operational results for the fiscal year ended 30 September 2021

Exhibit 99.1 Arqit Quantum Inc. announces financial and operational results for the fiscal year ended 30 September 2021 ? Successful full commercial launch immediately prior to 2021 fiscal year end ? Billings commenced in Q4 of fiscal 2021 ? Sales pipeline growing and identified opportunities moving through sales cycle ? Business momentum in keeping with management expectations London, UK ? 16 Dec

December 16, 2021 POS AM

As filed with the Securities and Exchange Commission on December 16, 2021

Table of Contents As filed with the Securities and Exchange Commission on December 16, 2021 Registration No.

December 16, 2021 EX-4.8

Form of Rollover Option Agreement relating to the grant of an EMI option to acquire shares in Arqit Quantum Inc.

Exhibit 4.8 Form of Rollover Option Agreement Relating to the grant of an EMI option to acquire shares in ArQit Quantum Inc. between ArQit Limited ArQit Quantum Inc. and [Name of Optionholder (A)] ? White & Case LLP 5 Old Broad Street London EC2N 1DW ? ? Table of Contents ? ? ? ? ? Page 1. DEFINITIONS AND INTERPRETATION 2 2. GRANT OF THE OPTION AND RELEASE 5 3. NON-ASSIGNABILITY 5 4. RESTRICTIONS

December 9, 2021 SC 13D/A

ARQQ / Arqit Quantum Inc / Heritage Assets SCSp. - SC 13D/A Activist Investment

UNITED STATES SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1)* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares, $0.0001 par value per share (Title of Class of Securities) G0567U101 (CUSIP Number) Heritage Assets SCSp c/o Heritage Services SAM 7 rue du Gabian - 98000 Monaco Attention: Cristina Levis +377 97 97 63 1

October 12, 2021 SC 13D/A

ARQQ / Arqit Quantum Inc / D2BW Ltd - SC 13D/A Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1) ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U101 (CUSIP Number) D2BW Limited c/o Arqit Limited 1st Floor, 3 More London Riverside London SE1 2RE United Kingdom +44 203 91 70155 (Name, Address and Telephone Numbe

October 12, 2021 424B3

ARQIT QUANTUM INC. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants

TABLE OF CONTENTS ?Filed Pursuant to Rule 424(b)(3)? ?Registration No. 333-259982? PROSPECTUS ARQIT QUANTUM INC. 117,925,000 Ordinary Shares 6,266,667 Warrants to Purchase Ordinary Shares 14,891,640 Ordinary Shares Underlying Warrants This prospectus relates to the offer and sale from time to time by the selling securityholders named in this prospectus (the ?Selling Securityholders?) of up to 117,

October 12, 2021 CORRESP

[Signature page follows]

October 12, 2021 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Technology 100 F Street, NE Washington, D.

October 8, 2021 EX-10.5

Form of Amended and Restated Lock-up Agreement.

Exhibit 10.5 FORM OF AMENDED AND RESTATED LOCK-UP AGREEMENT THIS AMENDED AND RESTATED LOCK-UP AGREEMENT (this ?Agreement?) is made and entered into as of October 4, 2021 between (i) Arqit Quantum Inc., a Cayman Islands exempted limited liability company (?Pubco?) and (ii) the undersigned (the ?Holder?). Pubco and the Holder are sometimes referred to herein individually as a ?Party? and, collective

October 8, 2021 F-1/A

As filed with the Securities and Exchange Commission on October 8, 2021

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on October 8, 2021 Registration No.

October 6, 2021 LETTER

LETTER

United States securities and exchange commission logo October 6, 2021 David Williams Chief Executive Officer Arqit Quantum Inc.

October 4, 2021 6-K

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 October 2021 Commission File Number: 001-40

6-K 1 tm2127896d46k.htm FORM 6-K 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 October 2021 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 More London Riverside Lond

October 4, 2021 EX-99.1

ARQIT FOUNDERS VOLUNTARILY EXTEND LOCK-UP Signals Long-Term Commitment

Exhibit 99.1 ARQIT FOUNDERS VOLUNTARILY EXTEND LOCK-UP Signals Long-Term Commitment London, UK ? 4 October 2021 - Arqit Quantum Inc. (the ?Company?) today announces that the former shareholders of Arqit Limited and Centricus Heritage, LLC, the sponsor of Centricus Acquisition Corp., have voluntarily entered into new lock-up agreements with the Company to signal their long-term support of the Compa

October 1, 2021 F-1

Power of Attorney (included on signature page of the Registration Statement).

Table of Contents As filed with the Securities and Exchange Commission on October 1, 2021 Registration No.

September 21, 2021 SC 13D

ARQQ / Arqit Quantum Inc / Evolution Technology Fund II, SCSP. - SCHEDULE 13D Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 Arqit Quantum Inc. (Name of Issuer) Ordinary Shares, $0.0001 par value per share (Title of Class of Securities) G0567U101 (CUSIP Number) The Evolution Technology Fund II SCSp Bld F.W. Raiffeisen 15 2411 Luxembourg Luxembourg Attention: Dennis Smith Tel: +41 7979 46387 (Nam

September 17, 2021 EX-99.1

Joint Filing Agreement, dated as of September 17, 2021, by and among the Reporting Persons.

Exhibit 99.1 JOINT FILING AGREEMENT In accordance with Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with each of the Reporting Persons (as such term is defined in the Schedule 13D referred to below) on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the ordin

September 17, 2021 SC 13D

ARQQ / Arqit Quantum Inc / D2BW Ltd - SCHEDULE 13D Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 ARQIT QUANTUM INC. (Name of Issuer) ORDINARY SHARES (Title of Class of Securities) G0567U101 (CUSIP Number) D2BW Limited c/o Arqit Limited 1st Floor, 3 More London Riverside London SE1 2RE United Kingdom +44 203 91 70155 (Name, Address and Telephone Number of Person Author

September 14, 2021 EX-99.1

Joint Filing Agreement, dated as of September 13, 2021, by and among Heritage Assets, M Management and Manfredi Lefebvre d’Ovidio.

Exhibit 1 Joint Filing Agreement In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended (the ?Exchange Act?), the undersigned hereby agree to the joint filing on behalf of each of them of a Statement on Schedule 13D (including any and all amendments thereto, the ?Schedule 13D?) relating to the ordinary shares, $0.

September 14, 2021 SC 13D

ARQQ / Arqit Quantum Inc / Heritage Assets SCSp. - SC 13D Activist Investment

UNITED STATES SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. )* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares, $0.0001 par value per share (Title of Class of Securities) G0567U101 (CUSIP Number) Heritage Assets SCSp c/o Heritage Services SAM 7 rue du Gabian - 98000 Monaco Attention: Cristina Levis +377 97 97 63 19

September 13, 2021 SC 13D

ARQQ / Arqit Quantum Inc / Centricus Heritage LLC - SC 13D Activist Investment

UNITED STATES SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. )* Arqit Quantum Inc. (Name of Issuer) Ordinary Shares, $0.0001 par value per share (Title of Class of Securities) G0567U101 (CUSIP Number) Centricus Heritage LLC c/o Maples Corporate Services Limited P.O. Box 309, Ugland House, Grand Cayman, KY1-1104, Cayman

September 10, 2021 EX-2.4

Assignment, Assumption and Amendment Agreement for Centricus’ outstanding warrants, incorporated by reference to Exhibit 2.4 to the Registrant’s Shell Company Report on Form 20-F filed with the SEC on September 10, 2021.

Exhibit 2.4 ASSIGNMENT, ASSUMPTION AND AMENDMENT AGREEMENT (WARRANT AGREEMENT) This Assignment, Assumption and Amendment Agreement (this ?Agreement?) is made as of September 2, 2021, by and among Centricus Acquisition Corp., an exempted limited liability company incorporated under the laws of the Cayman Islands (the ?Company?), Arqit Quantum Inc., a Cayman Islands exempted limited liability compan

September 10, 2021 EX-4.2

Form of Lockup Agreement between the Company and the shareholders of Arqit Limited.

Exhibit 4.2 FORM OF LOCK-UP AGREEMENT (ARQIT LIMITED SHAREHOLDERS) THIS LOCK-UP AGREEMENT (this ?Agreement?) is made and entered into as of between (i) Arqit Quantum Inc., a Cayman Islands exempted limited liability company (?Pubco?) and (ii) the undersigned (the ?Holder?). Pubco and the Holder are sometimes referred to herein individually as a ?Party? and, collectively, as the ?Parties?. Any capi

September 10, 2021 EX-15.3

Consent of PKF Littlejohn LLP, independent registered public accounting firm of the Company.

EX-15.3 11 tm2127142d1ex15-3.htm EXHIBIT 15.3 Exhibit 15.3 Consent of Independent Registered Public Accounting Firm We consent to the use of our report dated May 28, 2021 with respect to the consolidated financial statements of Arqit Limited included in the shell company report on Form 20-F of Arqit Quantum Inc. dated September 10, 2021. We also consent to the reference to our Firm under the headi

September 10, 2021 EX-4.1

Registration Rights Agreement, by and among the Company and the other parties thereto, incorporated by reference to Exhibit 4.1 to the Company’s Shell Company Report on Form 20-F, filed with the SEC on September 10, 2021.

Exhibit 4.1 REGISTRATION RIGHTS AGREEMENT This Registration Rights Agreement is entered into as of 3 September 2021, by and among (i) Arqit Quantum Inc., a company incorporated in the Cayman Islands (the ?Company?), (ii) the parties listed on Schedule A hereto (each such party, together with Centricus Heritage LLC, a Cayman Islands limited liability company (the ?Sponsor?) and any person or entity

September 10, 2021 EX-1.1

Amended and Restated Memorandum and Articles of Association of the Company, incorporated by reference to Exhibit 1.1 to the Company’s Shell Company Report on Form 20-F, filed with the SEC on September 10, 2021.

EX-1.1 2 tm2127142d1ex1-1.htm EXHIBIT 1.1 Exhibit 1.1 THE COMPANIES ACT (AS REVISED) OF THE CAYMAN ISLANDS COMPANY LIMITED BY SHARES AMENDED AND RESTATED MEMORANDUM AND ARTICLES OF ASSOCIATION OF ARQIT QUANTUM INC. (ADOPTED BY SPECIAL RESOLUTION DATED AUGUST 30, 2021 AND EFFECTIVE ON SEPTEMBER 2, 2021) 1 THE COMPANIES ACT (AS REVISED) OF THE CAYMAN ISLANDS COMPANY LIMITED BY SHARES MEMORANDUM OF A

September 10, 2021 EX-15.2

Consent of Marcum LLP, independent registered public accounting firm of Centricus.

Exhibit 15.2 Independent Registered Public Accounting Firm’s Consent We consent to the incorporation by reference in this Shell Company Report of Arqit Quantum Inc. on Form 20-F of our report dated March 31, 2021, with respect to our audit of the financial statements of Centricus Acquisition Corp. as of December 31, 2020 and for the period from November 24, 2020 (inception) through December 31, 20

September 10, 2021 20-F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20-F (Mark One) ? REGISTRATION STATEMENT PURSUANT TO SECTION 12(B) OR 12(G) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 193

September 10, 2021 EX-4.8

Form of Director and Officer Indemnification Agreement, incorporated by reference to Exhibit 4.8 to the Company’s Shell Company Report on Form 20-F, filed with the SEC on September 10, 2021.

Exhibit 4.8 Form of Director and Officer Indemnification Agreement THIS INDEMNITY AGREEMENT (this ?Agreement?) is made as of , 2021, by and between Arqit Quantum Inc., a Cayman Islands exempted company (the ?Company?), and (?Indemnitee?). RECITALS WHEREAS, highly competent persons have become more reluctant to serve publicly-held corporations as directors, officers or in other capacities unless th

September 10, 2021 EX-15.1

Unaudited pro forma combined financial information.

Exhibit 15.1 UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION Introduction Pursuant to the Business Combination Agreement dated May 12, 2021 (the “Business Combination Agreement”) by and among Arqit Quantum Inc. (the “Company”), Centricus Acquisition Corp. (“Centricus”), Centricus Heritage LLC, a Cayman Islands limited liability company, solely in its capacity as Centricus’ representative (the “

September 10, 2021 EX-4.3

Form of Lockup Agreement between the Company and the Sponsor.

Exhibit 4.3 FORM OF LOCK-UP AGREEMENT (SPONSOR) THIS LOCK-UP AGREEMENT (this ?Agreement?) is made and entered into as of September 3, 2021 between (i) Arqit Quantum Inc., a Cayman Islands exempted limited liability company (?Pubco?) and (ii) the undersigned (the ?Holder?). Pubco and the Holder are sometimes referred to herein individually as a ?Party? and, collectively, as the ?Parties?. Any capit

September 8, 2021 6-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

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 September 2021 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 More London Riverside London SE1 2RE, United Kingdom (Add

September 8, 2021 EX-99.1

Arqit Quantum Inc. (NASDAQ: ARQQ) Stronger simpler encryption September 2021

Exhibit 99.1 Arqit Quantum Inc. (NASDAQ: ARQQ) Stronger simpler encryption September 2021 2 Disclaimer The following presentation, the information communicated during any delivery of the presentation and any question and answer ses sion and any other materials distributed at or in connection with the presentation (collectively, this ?presentation?) has be en prepared by Arqit Quantum Inc. (?Arqit?

September 3, 2021 CERT

8A CERT

September 3, 2021 6-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

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 September 2021 Commission File Number: 001-40777 ARQIT QUANTUM INC. (Exact name of registrant as specified in its charter) 1st Floor, 3 More London Riverside London SE1 2RE, United Kingdom (Add

September 3, 2021 EX-99.1

Arqit and Centricus Announce Closing of Business Combination Trading on Nasdaq to commence on September 7, 2021 under the ticker “ARQQ”

EX-99.1 2 tm2126997d1ex99-1.htm EXHIBIT 99.1 Exhibit 99.1 Arqit and Centricus Announce Closing of Business Combination Trading on Nasdaq to commence on September 7, 2021 under the ticker “ARQQ” NEW YORK / LONDON (September 3, 2021) – Arqit Quantum Inc. (“Arqit”), a leader in quantum encryption technology, today announced the completion of its business combination with Centricus Acquisition Corp. (

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