SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Arqit Quantum Inc.

(Name of Issuer)

Ordinary Shares

(Title of Class of Securities)

G0567U127

(CUSIP Number)

06/26/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP Number(s):

G0567U127

Names of Reporting Persons

Notion Capital III LP

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

UNITED KINGDOM

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,812,206.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,812,206.00

Aggregate Amount Beneficially Owned by Each Reporting Person

1,812,206.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

10.0 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

Arqit Quantum Inc.

(b)

Address of issuer's principal executive offices:

3 Orchard Place, London, X0, W1H 0BF.

Item 2.

(a)

Name of person filing:

Notion Capital III LP

(b)

Address or principal business office or, if none, residence:

91 Wimpole Street, London, W1G 0EF, United Kingdom

(c)

Citizenship:

United Kingdom

(d)

Title of class of securities:

Ordinary Shares

(e)

CUSIP No.:

G0567U127

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:

(k)

Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

Item 4.

Ownership

(a)

Amount beneficially owned:

1,812,206(1)(2) Ordinary Shares (1) The share amounts in Item 4(a), (c)(ii), and (c)(iv) consist solely of Ordinary Shares of the Issuer that are held of record by Liberum Wealth Limited for the account of, and are beneficially owned by, Notion Capital III LP, and do not include any other securities of the Issuer that Liberum Wealth Limited may hold for its own account or for other clients. Such share amounts include 124 Ordinary Shares held by Notion Platform Limited and reflect the Reverse Share Split. (2) The share amounts in Item 4(a), (c)(ii), and (c)(iv) include 76,381 Ordinary Shares that could be obtained upon the conversion of 76,381 Registered Direct Warrants received in connection with the securities purchase agreement, dated September 8, 2023, by and among the Issuer and certain purchasers, with each Registered Direct Warrant providing the right to purchase one Ordinary Share at a price of $19.50 per share, after reflecting the Reverse Share Split. On June 26, 2026, the reporting person exercised in full the 600,000 September 2024 Warrants received in connection with the securities purchase agreement, dated September 30, 2024, by and among the Issuer and certain purchasers, with each September 2024 Warrant providing the right to purchase one Ordinary Share at a price of $2.50 per share, resulting in the issuance of 600,000 Ordinary Shares, all of which are included in the share amounts in Item 4(a), (c)(ii), and (c)(iv). Separately, on June 24, 2026, the reporting person sold 58,263 Ordinary Shares from its previously held Ordinary Shares.

(b)

Percent of class:

10.0% (3) (3) Percentage of class represented by amount in Item 4(a) is calculated based on 17,402,411 Ordinary Shares issued and outstanding as of May 19, 2026, as reported in the Issuer's prospectus supplement on Form 424B3 (Registration No. 333-259982) filed with the Securities and Exchange Commission on May 21, 2026, plus the 600,000 Ordinary Shares issued upon the exercise in full of the September 2024 Warrants, and after reflecting the Reverse Share Split, together with the 76,381 Ordinary Shares issuable upon exercise of the Registered Direct Warrants held by the reporting person that are deemed outstanding for the reporting person pursuant to Rule 13d-3(d)(1)(i).

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

(ii) Shared power to vote or to direct the vote:

1,812,206 (1)(2) (1) The share amounts in Item 4(a), (c)(ii), and (c)(iv) consist solely of Ordinary Shares of the Issuer that are held of record by Liberum Wealth Limited for the account of, and are beneficially owned by, Notion Capital III LP, and do not include any other securities of the Issuer that Liberum Wealth Limited may hold for its own account or for other clients. Such share amounts include 124 Ordinary Shares held by Notion Platform Limited and reflect the Reverse Share Split. (2) The share amounts in Item 4(a), (c)(ii), and (c)(iv) include 76,381 Ordinary Shares that could be obtained upon the conversion of 76,381 Registered Direct Warrants received in connection with the securities purchase agreement, dated September 8, 2023, by and among the Issuer and certain purchasers, with each Registered Direct Warrant providing the right to purchase one Ordinary Share at a price of $19.50 per share, after reflecting the Reverse Share Split. On June 26, 2026, the reporting person exercised in full the 600,000 September 2024 Warrants received in connection with the securities purchase agreement, dated September 30, 2024, by and among the Issuer and certain purchasers, with each September 2024 Warrant providing the right to purchase one Ordinary Share at a price of $2.50 per share, resulting in the issuance of 600,000 Ordinary Shares, all of which are included in the share amounts in Item 4(a), (c)(ii), and (c)(iv). Separately, on June 24, 2026, the reporting person sold 58,263 Ordinary Shares from its previously held Ordinary Shares.

(iii) Sole power to dispose or to direct the disposition of:

(iv) Shared power to dispose or to direct the disposition of:

Item 5.

Ownership of 5 Percent or Less of a Class.

Not Applicable

Item 6.

Ownership of more than 5 Percent on Behalf of Another Person.

Not Applicable

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group.

Not Applicable

Item 9.

Notice of Dissolution of Group.

Not Applicable

Item 10.

Certifications:

Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Notion Capital III LP

Signature:	/s/ Ian Milbourn
Name/Title:	Ian Milbourn, Designated Member of Notion Capital Managers LLP, for and on behalf of Notion Capital III GP LLP, its general partner
Date:	09/10/2026