Court invalidates four Ampyra patents; Acorda plummets 24%

• Acorda Therapeutics (NASDAQ:ACOR -23.9%) is under pressure after a Delaware district court ruled that four patents ('685, '826, '703 and '437) covering MS med AMPYRA (dalfampridine) are invalid. One patent ('938) was upheld.
• The company says it will appeal the decision.
• AMPYRA accounts for almost all of Acorda's sales, projected to be $535M - 545M this year.