Five biotechs exited the $1 billion-plus market cap space last year, while 10 new companies made the cut, resulting in a net inflow of five. As a result, 64 companies were above $1 billion in market cap at the end of 2012, compared with 59 at the end of 2011. Four of the companies were acquired last year - Amylin Pharmaceuticals Inc., Gen-Probe Inc., Human Genome Sciences Inc. and Pharmasset Inc. The fifth company fell out of the group: the market value for Dendreon Corp. (NASDAQ:DNDN) dropped 29% to $791.3 million at year end.

The 10 tier-jumpers were Arena Pharmaceuticals Inc. (NASDAQ:ARNA), ImmunoGen Inc. (NASDAQ:IMGN), Infinity Pharmaceuticals Inc. (NASDAQ:INFI), Integra LifeSciences Holdings Corp. (NASDAQ:IAR), Isis Pharmaceuticals Inc. (NASDAQ:ISIS), Lexicon Pharmaceuticals Inc. (NASDAQ:LXRX), Swedish Orphan Biovitrum AB (SSE:SOBI), Synageva BioPharma Corp. (NASDAQ:GEVA), ThromboGenics N.V. (Euronext:THR) and Vivus Inc. (NASDAQ:VVUS). Probably the most notable tier-jumper was Gilead Sciences Inc. (NASDAQ:GILD), which lept 76% during 2012 to $55.8 billion in market value. It rejoined Amgen Inc. (NASDAQ:AMGN, $66 billion in market cap) as the biotechs in the space above $50 billion. Gilead last crossed this threshold in 2008. The tally excludes research suppliers and service providers, unless the company is also focused on diagnostics, in which case it is included. Source: BCIQ: BioCentury Online Intelligence