"It is fair to say this raises questions" with the FBI, said agency spokesman Ross Rice. "There could be a violation if there's a payout and if the operators take a cut."
Even before the NCAA men's Division I basketball tournament begins next week, more than 20,000 online pools are circulating on Facebook, which has roughly 70 million members. Many of the tourney pools have just one or two members at this point—the organizers—but other groups have already reached the hundreds.
It is unclear how many are asking for money to play, but at least several are.