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

Deutsche Balaton Aktiengesellschaft

City of registered office (if applicable)

Heidelberg

Country of registered office (if applicable)

Germany

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

27-Mar-2023

6. Date on which Issuer notified

28-Mar-2023

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

. % of voting % of voting Total of both in Total number of rights attached rights through % (8.A + 8.B) voting rights to shares financial held in issuer (total of 8.A) instruments (total of 8.B 1 + 8.B 2) Resulting 17.022612 0.000000 17.022612 2096756 situation on the date on which threshold was crossed or reached Position of 16.111665 0.081185 16.192850 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 745038 1351718 6.048624 10.973988 Sub Total 8.A 2096756 17.022612%

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

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

Ultimate Name of controlled % of voting % of voting Total of both controlling undertaking rights if it rights through if it equals or person equals or is financial is higher than higher than instruments if the notifiable the notifiable it equals or is threshold threshold higher than the notifiable threshold Wilhelm K.T. Zours Wilhelm K.T. DELPHI 5.183175 5.183175% Zours Unternehmensberatung Aktiengesellschaft Wilhelm K.T. Deutsche Balaton 6.048624 6.048624% Zours Aktiengesellschaft Wilhelm K.T. SPARTA AG 10.973988 10.973988% Zours

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

Wilhelm K. T. Zours controls circa 49.7% of 2invest AG, who in turn holds 30% of the voting rights of 4basebio PLC.

12. Date of Completion

13. Place Of Completion

Heidelberg, Germany

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