Annexon, Inc. (Nasdaq: ANNX), a clinical-stage biopharmaceutical company developing a new class of complement medicines for patients with classical complement-mediated autoimmune, neurodegenerative and ophthalmic disorders, today announced that it has entered into a securities purchase agreement for a private placement that is expected to result in gross proceeds of approximately $130 million, before deducting placement agent fees and other expenses. The private placement was led by Redmile Group, LLC, with participation by Adage Capital Partners LP, Bain Capital Life Sciences, Driehaus Capital Management, Fairmount, Satter Medical Technology Partners and Venrock Healthcare Capital Partners.