On April 15, 2011, the U.S. Attorney's Office for the Southern District of New York seized and shut down Pokerstars and several of its competitors' sites, alleging that the sites were violating federal bank fraud and money laundering laws.
The bubble is the stage of a tournament when there is one more player left in than places paid. In a standard single table tournament (STT), the first three places earn a slice of the prize-money, therefore the bubble occurs when four players remain.