Exhibit 99.1 Annexon Reports First Quarter 2026 Financial Results, Portfolio Progress and Key Anticipated Milestones Topline Pivotal Phase 3 Data for Vonaprument for the Treatment of Geographic Atrophy (GA) Expected Q4 2026, with Potential to Redefine Vision Preservation in GA Tanruprubart EU Marketing Authorization Application (MAA) Under Review as the Potentially First Targeted Therapy for Guillain- Barré Syndrome (GBS); Biologics License Application (BLA) Submission with U.S./European FORWARD Data Expect ...