On a day when the Nasdaq has fallen more than 3.5% (as of this writing) shares of Biogen IDEC (NASDAQ:BIIB) were up more than 6%, but with nary a press release in sight.

The reason for the gains in shares of Biogen, which was up almost 9% at one point today, is a Financial Times report that the first round of bidding to acquire Biogen is expected to be complete next week. No concrete bids or possible acquirers were announced; just the usual rumors of large-cap pharmas in need of a boost to their pipelines.

Any deal upward of the $23 billion that Biogen is expected to go for following investor Carl Icahn's per-share bid a few weeks ago of $78 and change looks expensive considering the other biopharma assets that are potentially up for grabs.

To help imagine how rich a $23 billion and above valuation for Biogen is, consider that even with a 50% premium to all of its current market capitalizations, for only $17 billion, a large pharma could acquire Millennium Pharmaceuticals (NASDAQ:MLNM), ImClone Systems (NASDAQ:IMCL), Exelixis (NASDAQ:EXEL), and PDL BioPharma (NASDAQ:PDLI) and gain access to at least 33 compounds in clinical stage testing, more in preclinical testing, and several approved oncology drugs like Millennium's Velcade and ImClone's Erbitux.

Biogen, on the other hand, has only 14 unapproved new molecular entities in its pipeline, according to its website. While Biogen does hold the blockbuster compounds Rituxan and Avonex, plus multiple sclerosis treatment Tysabri, there's no guarantee an acquirer would be able to keep two of the three compounds in a buyout (although they would be compensated if they lost them).

None of the above means that a desperate, large pharma won't stretch and make an outsized bid for Biogen though. The bottom line to me with all the Biogen bidding reports is that, while it's fun to follow and read about all the possible large-cap pharma targets, speculating on shares of any drugmaker based on the possibility of a buyout is often a losing strategy.

More Foolishness on drugmaker acquisitions:

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has an A+ disclosure policy.