Alexion Pharmaceuticals ( ALXN) is the fastest-growing stock on the list above. Its EPS grew at 87.72% on average annually during the past five years. It also has a high operating margin of 28.16%. Alexion is engaged in discovering, developing and commercializing therapeutic products aimed at treating patients with severe and life-threatening diseases. Its total revenue increased from only $1.56 million in 2006 to $541 million in 2010. ALXN was held by 20 hedge funds at the end of the third quarter. Andreas Halvorsen's Viking Global also bought $46 million worth of new ALXN shares during the third quarter. Jim Simons' Renaissance Technologies had $23.4 million invested in ALXN at the end of September. We like healthcare stocks. Healthcare is still growing faster than the rest of the economy and National Health Expenditures (NHE) as a share of GDP is expected to reach 19.6% by 2019. We think health care is a promising sector and we encourage investors to do some in-depth research on the profitable healthcare stocks for their portfolios. >>To see these stocks in action, visit the 10 Health Care Stocks to Watch portfolio on Stockpickr.