Exhibit 99.1 Annexon Reports First Quarter 2024 Financial Results and Key Anticipated Milestones Multiple Value-creating Catalysts Across the Annexon Portfolio Throughout 2024 Pivotal Phase 3 Data for ANX005 in Guillain-Barré Syndrome (GBS) Expected in Second Quarter 2024; Potential to be the First Targeted Treatment for GBS New Phase 2 Data Showing Neuroprotection of Vision and Vision-Associated Structures by ANX007 in Geographic Atrophy (GA) Presented at ARVO 2024; Initiation of Pivotal Phase 3 ANX007 ARC ...