144 0001862930 XXXXXXXX LIVE 0001826457 MONTE ROSA THERAPEUTICS INC 001-40522 321 Harrison Avenue, Suite 900 Boston MA 02118 617-949-2643 FILIP JANKU Officer Common Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 8th Floor New York NY 10004

30000 621300.00 84479418 06/24/2026 NASDAQ Common 06/24/2026 Exercise of Stock Options Issuer N 30000 06/24/2026 Cash N 10b5-1 Sales for FILIP JANKU

321 Harrison Avenue, Suite 900 Boston MA 02118

Common 06/23/2026 11845 239522.50 The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale. 06/24/2026 03/04/2026 /s/ Filip Janku