Assembly Biosciences is a clinical-stage biotech developing oral antiviral drugs for serious viral diseases. Assembly has no approved products and generates no product revenue. Its pipeline includes four programs: two helicase-primase inhibitors (HPIs) for recurrent genital herpes, an oral entry inhibitor for hepatitis delta virus (HDV), a capsid assembly modulator for hepatitis B virus (HBV), and a broad-spectrum polymerase inhibitor targeting multiple herpesviruses in transplant patients. Assembly's business model centers on advancing drug candidates through early-to-mid clinical stages, then licensing them to partners for late-stage development and commercialization. The cornerstone of this model is a collaboration with Gilead, signed in October 2023, under which Gilead paid $84.8M upfront plus a $15.2M equity investment and contributed two programs to Assembly in exchange for options on Assembly's current and future pipeline. Gilead pays $75M in extension fees at the third, fifth, and seventh anniversaries of the collaboration, and can license individual programs upon Phase 1 completion for $45M–$125M per program. In December 2025, Gilead exercised its option on the HPI program. For licensed programs, Assembly is eligible for up to $330M in milestones plus tiered royalties, or can opt into a 40% U.S. profit share. Assembly outsources manufacturing and clinical operations, keeping headcount lean at 73 employees.