Earnout provisions in acquisition agreements can be a useful tool in bridging the valuation gap by deferring portions of the purchase price until certain post-closing milestones are achieved, and they are particularly common in developmental-stage pharmaceutical transactions.  Practitioners should take note of the September 5, 2024 opinion in Shareholder Representative Services LLC v. Alexion Pharmaceuticals, Inc., in which the Delaware Court of Chancery held a buyer, Alexion, liable for breach of contract both for its failure to use commercially reasonable efforts to achieve milestones for which future earnout payments may have become due and for its failure to pay an earned milestone payment to selling securityholders of Syntimmune, Inc.[1]