Shares of Alexion Pharmaceuticals Inc (ALXN.O) soared 27 percent to a life-high after the company forecast $2 billion in sales for its blood disorder drug this year ahead of analysts' average estimate.
The company, which is also expected to benefit from a lower tax rate, reported sales of $1.55 billion for the drug, Soliris, in 2013.
Analysts on average were expecting sales of $1.96 billion for the company's sole drug this year.
Alexion said on Thursday it expected its adjusted tax rate to come down to 10-11 percent in 2014. The company is centralizing its global supply chain operations in Ireland and buying a vialing facility there.
"Now, essentially, their operations are mostly in Ireland, which makes it more tax-efficient. They don't have to pay U.S. taxes, so that lowers their taxes from about 32 percent," Janney Capital analyst Kimberly Lee said.
Morningstar analyst Stefan Quenneville said the shift would "have a significant effect on their bottom line."
Alexion forecast 2014 adjusted earnings of $3.70 to $3.80 per share, higher than analysts' average estimate of $3.46.
Sales from Soliris rose about 38 percent to $441.9 million in the fourth quarter ended December 31.
Analysts on average had expected sales of $430.7 million, according to Thomson Reuters I/B/E/S.
Alexion is able to command a hefty price for Soliris as the drug is the only approved treatment for two rare, life-threatening blood disorders.
The drug is also being developed for other "orphan" indications, or conditions that affect less than 200,000 people in the United States. Such a status allows the company that is first to market seven years of exclusivity.
Net loss for the fourth quarter was $19 million, or 10 cents per share, including a $95.8 million non-cash tax expense and a $33.5 million expense related to impairment of intangible assets.
Excluding items, the company earned 87 cents per share, beating the analysts' average estimate of 83 cents per share.
Shares of the company were up 22 percent at $163.35 in afternoon trading on the Nasdaq. The stock hit a life-high of $169.98 earlier.
More than 4.7 million shares changed hands, nearly 4 times their 10-day moving average.
(Reporting by Vrinda Manocha in Bangalore; Editing by Savio D'Souza and Sriraj Kalluvila)