Medivation ($MDVN)
Market cap: $3.5 billion

The scoop: Nothing succeeds at spurring buyout speculation these days better than development success. For Medivation, its success at the FDA with Xtandi (enzalutamide) in August quickly inspired talk of a buyout by Astellas, Medivation's marketing partner on the drug. But even AbbVie, the Abbott ($ABT) spinoff, and AstraZeneca (of course) could be in the running.

For its part, Medivation execs have repeated over and over again that they're going all the way, building a full-fledged company with blockbuster revenue and a pipeline of products. The management team put a poison pill in place to make its position crystal clear, but poison pills can't keep away a determined suitor.

At least one of the most frequently cited potential bidders, AstraZeneca ($AZN), has the kind of patent cliff issues that will drive some hefty bids when it has a new product in sight. But Jefferies analyst Biren Amin has attracted attention for his belief that any company competing for prostate cancer business--including J&J ($JNJ)--could be interested, provided they don't run into antitrust concerns. And he's also mentioned Sanofi ($SNY) and Amgen ($AMGN) as possible bidders, though that could just as easily be translated into just about any Big Pharma company looking for a tasty takeover target.

Medivation hasn't always had it this good. The company had to grapple with the high-profile failure of the Alzheimer's drug Dimebon. But Medivation did just about everything right when it comes to Xtandi. If it can start ringing bells on the sales side and add some intriguing new programs to its pipeline, it could prove either too tempting to ignore or too expensive to pick up easily.

For more:
Medivation wins FDA OK for blockbuster prostate cancer drug
Who's next on Big Pharma's biotech shopping list?