The question of what kinds of plus factors are sufficient, and what are not, is interesting. Courts have treated all sorts of things — opportunity and motive to conspire are pernicious examples — as “plus factors.” That does not mean they even approach the plausibility standard. Professor Page has an interesting recent article noting that the definition of sufficient plus factors should boil down to allegations of “communication.”

Finally, regarding expert analysis, it’s an interesting conundrum. On the one hand, if the substantive rule of law (per Matsushita) prescribes economic rationality, it seems fair to require in the complaint that somebody schooled in economics speak to the economic rationality of the conduct plaintiffs believe occurred. On the other hand, do we want judges to weigh expert testimony at the MTD stage? And if not, can any junk science overcome the Twombly problem?