Company Announcements

TR-1: Standard form for notification of major holdings

1. Issuer Details

ISIN

GB00BMCLYF79

Issuer Name

4BASEBIO PLC

UK or Non-UK Issuer

UK

2. Reason for Notification

An acquisition or disposal of voting rights

3. Details of person subject to the notification obligation

Name

Franciscus De Busschere

City of registered office (if applicable)

Beernem

Country of registered office (if applicable)

Belgium

4. Details of the shareholder

Full name of shareholder(s) if different from the person(s) subject to the notification obligation, above

City of registered office (if applicable)

Country of registered office (if applicable)

5. Date on which the threshold was crossed or reached

06-June-2024

6. Date on which Issuer notified

06-June-2024

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

                                % of voting
                % of voting     rights through                   Total number of
.               rights attached financial       Total of both in voting rights
                to shares       instruments     % (8.A + 8.B)    held in issuer
                (total of 8.A)  (total of 8.B 1
                                + 8.B 2)

Resulting
situation on
the date on     4.1956%         0.00%           4.1956%          537,255
which threshold
was crossed or
reached

Position of
previous
notification
(if applicable)

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    Number of direct Number of         % of direct   % of indirect
shares ISIN code voting rights    indirect voting   voting rights voting rights
(if possible)    (DTR5.1)         rights (DTR5.2.1) (DTR5.1)      (DTR5.2.1)

GB00BMCLYF79     471,502          65,753            3.6821%       0.5135%

Sub Total 8.A    537,255                            4.1956%

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

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

Sub Total 8.B1

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

Type of    Expiration Exercise/conversion Physical or Number of     % of voting
financial  date       period              cash        voting rights rights
instrument                                settlement

Sub Total
8.B2

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)

                                             % of voting rights
                          % of voting rights through financial  Total of both if
Ultimate      Name of     if it equals or is instruments if it  it equals or is
controlling   controlled  higher than the    equals or is       higher than the
person        undertaking notifiable         higher than the    notifiable
                          threshold          notifiable         threshold
                                             threshold

Franciscus De             3.6821%                               3.6821%
Busschere

Franciscus De FEEPA N.V.  0.5135%                               0.5135%
Busschere

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

12. Date of Completion

13. Place Of Completion

Beernem, Belgium