National Storage Mechanism | Additional information

TR-1: Standard form for notification of major holdings

1. Issuer Details

ISIN

GB0004726096

Issuer Name

SPIRENT COMMUNICATIONS PLC

UK or Non-UK Issuer

2. Reason for Notification

An acquisition or disposal of voting rights

3. Details of person subject to the notification obligation

Name

JPMorgan Chase & Co.

City of registered office (if applicable)

Country of registered office (if applicable)

4. Details of the shareholder

Name	City of registered office	Country of registered office
J.P. Morgan Securities plc

5. Date on which the threshold was crossed or reached

22-Sep-2025

6. Date on which Issuer notified

24-Sep-2025

7. Total positions of person(s) subject to the notification obligation

	% of voting rights attached to shares (total of 8.A)	% of voting rights through financial instruments (total of 8.B 1 + 8.B 2)	Total of both in % (8.A + 8.B)	Total number of voting rights held in issuer
Resulting situation on the date on which threshold was crossed or reached	4.949119	0.956106	5.905225	34828886
Position of previous notification (if applicable)	5.140604	0.883311	6.023915

8. Notified details of the resulting situation on the date on which the threshold was crossed or reached

8A. Voting rights attached to shares

Class/Type of shares ISIN code(if possible)	Number of direct voting rights (DTR5.1)	Number of indirect voting rights (DTR5.2.1)	% of direct voting rights (DTR5.1)	% of indirect voting rights (DTR5.2.1)
GB0004726096		29189799		4.949119
Sub Total 8.A	29189799		4.949119%

8B1. Financial Instruments according to (DTR5.3.1R.(1) (a))

Type of financial instrument	Expiration date	Exercise/conversion period	Number of voting rights that may be acquired if the instrument is exercised/converted	% of voting rights

Sub Total 8.B1

8B2. Financial Instruments with similar economic effect according to (DTR5.3.1R.(1) (b))

Type of financial instrument	Expiration date	Exercise/conversion period	Physical or cash settlement	Number of voting rights	% of voting rights
Cash-settled Equity Swap	28/11/2025	28/11/2025	Cash	1181324	0.200293
Cash-settled Equity Swap	15/04/2026	15/04/2026	Cash	1103450	0.187090
Cash-settled Equity Swap	19/08/2026	19/08/2026	Cash	240	0.000041
Cash-settled Equity Swap	26/08/2026	26/08/2026	Cash	46259	0.007843
Cash-settled Equity Swap	18/09/2026	18/09/2026	Cash	50714	0.008599
Cash-settled Equity Swap	06/10/2026	06/10/2026	Cash	1827150	0.309793
Cash-settled Equity Swap	19/10/2026	19/10/2026	Cash	13466	0.002283
Cash-settled Equity Swap	21/10/2026	21/10/2026	Cash	10403	0.001764
Cash-settled Equity Swap	30/05/2028	30/05/2028	Cash	238	0.000040
Cash-settled Equity Swap	02/05/2030	02/05/2030	Cash	1405843	0.238360
Sub Total 8.B2				5639087	0.956106%

9. Information in relation to the person subject to the notification obligation

2. Full chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held starting with the ultimate controlling natural person or legal entities (please add additional rows as necessary)

Ultimate controlling person	Name of controlled undertaking	% of voting rights if it equals or is higher than the notifiable threshold	% of voting rights through financial instruments if it equals or is higher than the notifiable threshold	Total of both if it equals or is higher than the notifiable threshold
JPMorgan Chase & Co.	J.P. Morgan Securities plc	4.949119		5.905224%
JPMorgan Chase & Co.	J.P. Morgan SE

10. In case of proxy voting

Name of the proxy holder

The number and % of voting rights held

The date until which the voting rights will be held

11. Additional Information

Chain of controlled undertakings:

JPMorgan Chase & Co.
JPMorgan Chase Bank, National Association (100%)
J.P. Morgan International Finance Limited (100%)
J.P. Morgan Capital Holdings Limited (100%)
J.P. Morgan Securities plc (100%)

JPMorgan Chase & Co.
JPMorgan Chase Bank, National Association (100%)
J.P. Morgan International Finance Limited (100%)
J.P. Morgan SE (100%)

12. Date of Completion

24-Sep-2025

13. Place Of Completion

London, United Kingdom