ASSEMBLY BIOSCIENCES, INC. (ASMB) stock intrinsic value fair value estimate & owner earnings analysis

Assembly Biosciences is a clinical-stage drug developer working on antiviral medicines. It has no approved products. Its income comes from its October 2023 partnership with Gilead Sciences. Its programs are: long-acting helicase-primase inhibitors for recurrent genital herpes (GS-1179 and GS-5366, licensed to Gilead in December 2025); ABI-6250, an oral hepatitis delta entry inhibitor that Assembly is also developing for cholestatic liver diseases; and ABI-4334, a hepatitis B capsid modulator that Gilead chose not to license and for which Assembly is looking for another partner. The record. Owner earnings (operating cash flow with working-capital swings and stock pay stripped out) were negative in every one of the last ten years, from about -$101 million in 2019 to about -$8 million in 2025. The 2025 figure looks small only because it includes Gilead's $35 million option payment and the gradual recognition of earlier upfront money as revenue. Cash used in operations was $37.6 million in the first half of 2026 alone. The company has funded itself by selling shares, most recently about $124 million net in August 2025 and about $108 million net in May 2026. At June 30, 2026 it held $320.4 million of cash and marketable securities, plus about $11 million from warrant exercises in July. There are about 21.8 million shares, including pre-funded warrants. The Gilead deal. Gilead paid $84.8 million in cash upfront and bought $15.2 million of stock. It can license each program for an opt-in fee of $45 million to $125 million. It also pays $75 million extension fees at the collaboration's third, fifth and seventh anniversaries, and it holds termination rights at set points. The company says the first $75 million payment is due in the fourth quarter of 2026. On September 8, 2026 Assembly chose to pay 40% of U.S. development costs for the herpes program in return for 40% of U.S. profits. It keeps eligibility for up to $280 million in milestones outside the U.S., plus royalties. Gilead controls that program and expects to start a Phase 2 trial of GS-1179 by the end of 2026. How we valued it. None of these programs has finished a Phase 2 trial. Milestones, royalties and the U.S. profit share all depend on trial results and approvals that have not happened, so none of them is counted in any case. That leaves the cash, the Gilead payments set by contract, and the cost of the planned work. The company says its cash will fund operations into 2029, and that plan includes the first $75 million payment. So the value is the cash on hand plus contracted receipts, less the present value of the spending that will use them up. Cash is assumed to earn about 3.7% while it waits and is discounted at 6%. Because the plan is to spend the money on trials, very little of today's cash is left for shareholders unless the science pays off. Base case: the October 2026 payment arrives. Spending rises from about $80 million a year now to about $135 million in 2027 and $155 million in 2028, as the herpes cost share and two ABI-6250 Phase 2 studies get under way. Cash runs out around late 2029. Value is about $34 million, or $1.55 a share. Bear case: trial costs run higher (about $160 million in 2027 and $185 million in 2028) because Gilead, not Assembly, sets the herpes budget. Cash runs out in 2029, for $1.33 a share. Bull case: spending stays nearer today's pace (about $100-110 million a year), and Gilead also pays the 2028 and 2030 extension fees. The money lasts to about 2032, for $2.56 a share. Outstanding warrants (about 3.7 million at $21.60 and 0.8 million at $17, plus 4.5 million Class B warrants that are cancelled if $75 million of partner money is announced before November 15, 2026) are left out. If exercised, they would add cash that would be spent the same way. What would make this wrong. The shares hold about $15 of cash each today. They would be worth far more than these cases if management stopped spending, or if GS-1179, GS-5366 or ABI-6250 succeeded in Phase 2 and started paying milestones or profits. We cannot credit either outcome from the evidence now available. The main risk the other way is that spending outlasts the cash and the company sells more shares to keep the trials going.