Why is AC Immune stock gaining today?

AC Immune's stock surged 3.4% in pre-market trading following a significant regulatory win from the FDA. The agency granted Fast Track designation to ACI-7104, the company's anti-alpha-synuclein active immunotherapy for early-stage Parkinson's disease. Simultaneously, the FDA cleared the Investigational New Drug application, allowing AC Immune's Phase 2 VacSYn trial to expand enrollment to U.S. clinical sites.

This dual approval was bolstered by interim data from Part 1 of the VacSYn trial, which showed a favorable safety profile with no concerning adverse effects. The news comes as AC Immune is set to present three neurodegeneration studies at the Alzheimer's Association International Conference in 2026. With full 104-week data from Part 1 anticipated in the second half of next year, investors appear to be positioning ahead of what could be another major data readout for the program.

The broader market, while mildly positive, did not drive the move in ACIU stock, which is now trading near its pre-market high of $2.37 and above the previous close of $2.28.