Shares in British drugsmaker Shire slumped more than 11 percent on Monday after US regulators approved a rival company to market a cheaper version of its hyperactivity drug Adderall XR.
Shire shares plunged 11.70 percent to stand at 1,736 pence -- heading the losers board on London's benchmark FTSE 100 index, which was down 0.96 percent at 5,460.59 points in afternoon trading.
The stock sank after US regulators ruled against Shire, which said in a statement that they had approved generic copies of Adderall XR from Watson Pharmaceuticals' recently acquired Actavis unit.
"Shire announces that the US Food and Drug Administration has responded to its citizen petition for Adderall XR and has approved one abbreviated new drug application for generic Adderall XR," Shire said in a statement.
-- Dow Jones Newswires contributed to this story --
Source: AFP Global Edition