The betting market Intrade, a popular site for political prognosticators, is now closed to Americans. 

"We are sorry to announce that due to legal and regulatory pressures, Intrade can no longer allow US residents to participate in our real-money prediction markets," the company said in a statement Monday. "Unfortunately this means that all US residents must begin the process of closing down their Intrade accounts. We strongly urge you to begin this process immediately."