144 0002005875 XXXXXXXX LIVE 0001719714 Mereo BioPharma Group plc 001-38452 4th Floor, One Cavendish Place London X0 W1G 0QF 44-333 023 7300 Alexandra Hughes-Wilson Officer American Depositary Shares Representing Ordinary Shares Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 38th Floor New York NY 10004

100432 297505.97 702493754 05/22/2024 Nasdaq American Depositary Shares Representing Ordinary Shares 05/22/2024 Share Option Exercise Issuer N 50350 05/22/2024 Cash American Depositary Shares Representing Ordinary Shares 05/22/2024 Share Option Exercise Issuer N 50082 05/22/2024 Cash Y The number of shares to be sold is in the form of American Depositary Shares ("ADSs"). The number of shares outstanding is in the form of ordinary shares. Each ADS represents 5 ordinary shares, nominal value GBP 0.003 per ordinary share, of the Issuer. 05/23/2024 /s/ Alexandra Hughes-Wilson