Novartis took a $1.9 billion partial impairment charge tied to the Phase 3 failure of Avidity Biosciences’ del-desiran, but the company said it remains committed to the $12 billion acquisition. CEO Vas Narasimhan pointed to evidence of clinical activity in secondary and exploratory endpoints in the HARBOR study as it evaluates what comes next. The write-down underscores how quickly late-stage outcomes can force repricing even after large M&A bets in ADC-adjacent platforms. Novartis also reiterated plans to advance other Avidity assets, including del-brax in Phase 3 for facioscapulohumeral muscular dystrophy and del-zota, which has priority review in Duchenne muscular dystrophy. For biotech operators, the episode highlights a key diligence gap for acquirers: how much “platform value” depends on one lead program’s ability to deliver a primary endpoint. Market reaction typically follows not just efficacy signals, but the timing and cost of restarting pivotal work—an issue Novartis said it is factoring into adjusted valuation.