Sell4

Arqit Quantum Inc.

ARQQ

Total Value

$12.4K

Net $12.4K sold

Filing Date

Oct 7, 2026

1 transaction

Sales

$12.4K

1 transaction

Trade Summary

On Oct 5, 2026, Nilan Nicholas William, General Manager-US, sold $12.4K of Arqit Quantum Inc. (ARQQ) across 1 transaction. The filing covers Ordinary Shares and reflects net selling of $12.4K. Reported prices ranged from $23.78. Insider transactions are sourced from SEC Form 4 disclosures and should be reviewed alongside company fundamentals and the insider's broader trading history.

Price at the Time of the Trade

ARQQ daily price with the insider's sale marked at $23.78.

Sold in the upper half of the 6-month range · the stock trades 15% lower today.

Price data is delayed and provided for context only — not investment advice.

Insider Information

Name: Nilan Nicholas William
Role: General Manager-US

Filing Details

Filing Date: Oct 7, 2026
Transaction Date: Oct 5, 2026
Accession Number: 0001859690-26-000181
Form Type: 4
Net Trading Amount: -$12.4K

Non-Derivative Transactions

Date	Security	Shares	Price	Type	Value
Oct 5, 2026	Ordinary Shares	959	—	Exercise	—
Oct 5, 2026	Ordinary Shares	522	$23.78	Sale	$12.4K

Derivative Transactions

Date	Security	Shares	Exercise Price	Type	Value
Oct 5, 2026	ARQQ derivative	959	—	Exercise	—

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Footnotes

(F1)The Restricted Share Units ("RSUs") convert into ARQQ ordinary shares on a one-for-one basis.
(F2)Each restricted stock unit ("RSU") represents a contingent right to receive one ARQQ ordinary share. 2,879 RSUs vested on October 1, 2026 and the remaining RSUs vest quarterly in equal installments on January 1, April 1, July 1, and October 1, 2027, and January 1, April 1, July 1, and October 1, 2028.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Nilan Nicholas William

(Last)

(First)

(Middle)

3 ORCHARD PLACE

(Street)

LONDON

SW1H 0BF

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
Arqit Quantum Inc. [ ARQQ ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	General Manager-US

3. Date of Earliest Transaction (Month/Day/Year)
10/05/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Ordinary Shares	10/05/2026		M		959	A	$0⁽¹⁾	1,863	D
Ordinary Shares	10/05/2026		S		522	D	$23.7847	904	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Restricted Share Units	⁽²⁾	10/05/2026		M			959	⁽²⁾	⁽²⁾	Ordinary Shares	959	$0	5,752	D

Explanation of Responses:

1. The Restricted Share Units ("RSUs") convert into ARQQ ordinary shares on a one-for-one basis.

2. Each restricted stock unit ("RSU") represents a contingent right to receive one ARQQ ordinary share. 2,879 RSUs vested on October 1, 2026 and the remaining RSUs vest quarterly in equal installments on January 1, April 1, July 1, and October 1, 2027, and January 1, April 1, July 1, and October 1, 2028.

Remarks:

Due to the Issuer's status as a foreign private issuer pursuant to Rule 3a12-3(b) under the Securities Exchange Act of 1934 (the "Act"), the reporting person's transactions in the Issuer's securities are exempt from Sections 16(b) and 16(c) of the Act.

	/s/ Noleen McDonnell, as Attorney-in-Fact	10/07/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

Form 4 as rendered by the SEC from accession 0001859690-26-000181.

Arqit Quantum Inc.

Trade Summary

Price at the Time of the Trade

Company Information

Insider Information

Filing Details

Non-Derivative Transactions

Derivative Transactions

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Footnotes

SEC Form 4

SEC Filing

Price at the Time of the Trade

SEC Form 4