5. Keryx Biopharmaceuticals ( KERX) ^NBI data by YCharts Keryx shares popped when the results from the Zerenex study in kidney dialysis patients were announced in January. Since then, the stock has traded mostly sideways on concerns about Keryx's ability to partner Zerenex and secure enough patent protection and market exclusivity to make the drug commercially viable. Will these five stocks maintain their performance through the remainder of 2013? It's impossible to predict, obviously, but it's interesting to note that Clovis, Acadia and MannKind weren't Top 5 stock performers for the year at the end of the first quarter. Three stocks that were on the list as of March 31 -- Hyperion Therapeutics ( HPTX), Oramed Pharmaceuticals ( ORMP) and Coronado BioSciences ( CNDO) -- have dropped off. Overall, 20 drug and biotech stocks have doubled in price this year. A factoid that may be interesting only to me: Celsion ( CLSN) is the worst-performing drug stock year to date, but is "only" down 80%. Rounding out the bottom five: Oxygen Biotherapeutics ( OXBT), Aveo Pharmaceuticals ( AVEO), Genvec ( GNVC) and Enzon Pharmaceuticals ( ENZN). >>To see these stocks in action, visit the Five Best-Performing Biotech Stocks of 2013 portfolio on Stockpickr.