2013 is panning out to be a strong year for $80 billion biotech giant Amgen ( AMGN). Shares of the firm have rallied nearly 23% year-to-date, outperforming the S&P 500 by a considerable margin, and that's on top of the 34% that shares increased during 2012. This week, AMGN is making news after finally getting the go-ahead to buy Onyx Pharmaceuticals ( ONXX) in a deal worth $10.4 billion. The crown jewel in the deal is Kyprolis, a cancer drug that's still in the early stages of its lifecycle. >>5 Big Trades You Can't Miss Amgen is no stranger to blockbuster drugs. Right now, the firm has more than five drugs that each bring in over $1 billion in sales. Amgen's expertise in biotechnology-based therapeutics is unique among firms its size. It gives the firm an advantage over smaller rivals in the amount of capital it's able to throw at a project. As a result, AMGN has around 20 new drug compounds in its early stage pipeline (not counting the addition of Kyprolis further downstream). This company is an expert at converting sales into cash. Around one-third of every dollar that Amgen brings in gets converted into free cash, the result of hefty profit margins and economies of scale in Amgen's business. With increasing analyst sentiment pouring into shares this week, AMGN tops our list.