"With sincere regret we must inform you that due to circumstances recently discovered we must immediately cease trading activity, " Intrade said in its statement, saying the shutdown had been required under Irish law.

BBC: Intrade shuts amid investigation

In the event of a shutdown, some 800, 000 federal workers would be furloughed, while those required for the delivery of essential services would remain on the job.

FORBES: How A Government Shutdown Will Impact Wall Street And Your Finances