v3.26.1
Discontinued operations and assets held for sale - Result from discontinued operations (Details) - EUR (€)
€ / shares in Units, shares in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of analysis of single amount of off-balance sheet arrangements [line items]      
Collaboration revenues € 1,082,324,000 € 240,786,000 € 239,724,000
Total net revenues 1,112,248,000 275,649,000 239,724,000
Cost of sales (29,736,000) (34,863,000)  
Research and development expenses (459,421,000) (335,459,000) (241,294,000)
Sales and marketing expenses (6,100,000) (17,193,000) (5,676,000)
General and administrative expenses (147,333,000) (117,245,000) (128,289,000)
Other operating income 53,493,000 40,773,000 47,272,000
Other income 53,493,000 40,773,000 47,272,000
Operating loss 295,039,000 (188,338,000) (88,263,000)
Fair value adjustments and net currency exchange differences (39,356,000) 95,795,000 16,252,000
Other financial income 48,051,000 91,128,000 80,249,000
Other financial expenses (2,863,000) (1,670,000) (2,613,000)
Income/loss before tax 300,871,000 (3,085,000) 5,625,000
Net income from discontinued operations € 1,392,000 € 75,364,000 € 215,685,000
Weighted average number of shares - Basic 65,897 65,897 65,884
Weighted average number of shares for the purpose of diluted earnings/loss (-) per share 65,897 65,897 65,884
Discontinued Operations [Member]      
Disclosure of analysis of single amount of off-balance sheet arrangements [line items]      
Product net sales   € 11,475,000 € 112,339,000
Collaboration revenues   26,041,000 431,465,000
Total net revenues   37,516,000 543,804,000
Cost of sales   (1,693,000) (18,022,000)
Research and development expenses € (11,708,000) (8,152,000) (190,177,000)
Sales and marketing expenses (932,000) (11,520,000) (113,356,000)
General and administrative expenses (94,000) (1,087,000) (17,989,000)
Other operating income 11,933,000 56,180,000 13,003,000
Operating loss (801,000) 71,244,000 217,262,000
Fair value adjustments and net currency exchange differences     (13,000)
Other financial income 2,676,000 4,230,000 679,000
Other financial expenses   (12,000) (167,000)
Income/loss before tax 1,875,000 75,462,000 217,761,000
Income taxes (483,000) (98,000) (2,076,000)
Net income from discontinued operations € 1,392,000 € 75,364,000 € 215,685,000
Basic earnings/loss (-) per share from discontinued operations € 0.02 € 1.14 € 3.27
Diluted earnings/loss (-) per share from discontinued operations. € 0.02 € 1.14 € 3.27
Weighted average number of shares - Basic 65,897 65,897 65,884
Weighted average number of shares for the purpose of diluted earnings/loss (-) per share 65,901 65,942 65,933
Jyseleca business, classified as held for sale      
Disclosure of analysis of single amount of off-balance sheet arrangements [line items]      
Collaboration revenues   € 26,000,000  
Gain on disposal of subsidiaries   € 52,500,000