Company: Actelion ($ATLN)
Based: Allschwil, Switzerland
R&D budget: $539M (CHF 484.3M)
Change from 2009: +2.6%
Net revenue spent on R&D: 25%

Much of Actelion's sizable R&D budget goes to support its late-stage program for macitentan, a promising new drug for pulmonary arterial hypertension. Analysts say macitentan represents Actelion's best hope for gaining a blockbuster successor to the lung drug Tracleer, which earned $1.5 billion in 2010. Helvea analyst Olav Zilian has estimated macitentan peak sales at $1.41 billion.

Just how important is PAH for Actelion? Macitentan failed a mid-stage study for IPF this year and the biotech's shares still went up a bit. The reason: The data, while a loser on the efficacy side for IPF, demonstrated clear safety and tolerability, helping to ease a big cause of concern for the PAH study.

Actelion has other, more distant, shots on goal. In August, the developer announced positive Phase IIb data for its MS drug ponesimod, setting up a late-stage program. That kind of positive data has stirred up some M&A scuttlebutt, with Amgen rumored to be a potential interested buyer. But those kinds of stories always follow companies of this size.

Actelion's persistent management has had to fight off an attempted board coup and watch its shares slide as its big earner Tracleer continues to lose market share. It hasn't helped that the Greeks are paying the company with the country's junk bonds. That all leaves Actelion on tenterhooks as it waits for late-stage macitentan data in the first half of 2012.