Wall Street starts the week with a rally.
The Dow is up more than 250 points.
Wall Street moves higher.
The New Haven, Conn.-based firm on Sept. 9 received a termination notice regarding its license and collaboration pact with Johnson & Johnson's Janssen Pharmaceuticals Inc. on hepatitis C.
Thursday's downgrade is in part based on a lack of confidence in Achillion's CH-4471 to compete with Alexion Pharmaceuticals' Soliris treatment.