BOSTON ( TheStreet) -- Sanofi-Aventis ( SNY) might be in the market for a $20 billion-plus acquisition, or so says Bloomberg this morning, but is the French drug maker really targeting a large-cap biotech? I can think of some reasons to doubt it. Biogen Idec ( BIIB)? Sure, Carl Icahn has wanted to sell the company for years, but Biogen just named a new CEO this week. Would that have happened if the company was for sale? Plus, if Sanofi wants a drug pipeline, Biogen isn't the ideal candidate since one of the company's weaknesses is its anemic, internal drug research efforts. That's one of the reasons why George Scangos, a scientist, was recruited to be the new Biogen chief executive. Genzyme ( GENZ)? Does Sanofi really want to buy an FDA manufacturing consent decree? That's what you get with Genzyme, which can't seem to keep its drug manufacturing plants running without something breaking down. Yes, Genzyme has taken concrete steps towards fixing its manufacturing woes, but Sanofi would have take a big leap of faith before making an acquisition like this. I don't see a deal here happening. Gilead Sciences ( GILD)? If Sanofi truly wants to buy a "biotech" firm, meaning a company with the capacity and know-how to develop and manufacture biologic drugs, Gilead is not the fit since it deals exclusively in the small-molecule arena. Celgene ( CELG)? Perhaps if Sanofi wants to reclaim its once-dominant position in the cancer drug market, but then Celgenge just acquired Abraxis BioSciences ( ABII) this week. Doesn't that signal that Celgene is decidedly not in play? Amgen ( AMGN)? Too big. To me, that leaves Allergan ( AGN). Not a biotech, but it does provide nice diversification for Sanofi. -- Reported by Adam Feuerstein in Boston. Follow Adam Feuerstein on Twitter.