Gilead Sciences, Inc. and Pharmasset, Inc. have signed a definitive agreement under which Gilead will acquire Pharmasset in a transaction valued at $11 billion. Gilead plans to finance the transaction with cash, bank debt and senior unsecured notes. The transaction is expected to close in 1Q12. Pharmasset has three clinical-stage product candidates for the treatment of chronic hepatitis C virus (HCV) advancing in trials in various populations. The company’s lead product candidate, PSI-7977, has...