A Ponzi scheme is a fraudulent investment operation that pays returns to separate investors, not from any actual profit earned by the organization, but from their own money or money paid by subsequent investors. The Ponzi scheme usually entices new investors by offering returns other investments cannot guarantee, in the form of short-term returns that are either abnormally high or unusually consistent. The perpetuation of the returns that a Ponzi scheme advertises and pays requires an ever-increasing flow of money from investors to keep the scheme going.
The system is destined to collapse because the earnings, if any, are less than the payments to investors. Usually, the scheme is interrupted by legal authorities before it collapses because a Ponzi scheme is suspected or because the promoter is selling unregistered securities. As more investors become involved, the likelihood of the scheme coming to the attention of authorities increases. While the system eventually will collapse under its own weight, the example of Bernard Madoff's investment scandal demonstrates the ability of a Ponzi scheme to delude both individual and institutional investors as well as securities authorities for long periods: Madoff's variant of the Ponzi scheme stands as the largest financial investor fraud committed by a single person in history. Prosecutors estimate losses at Madoff's hand totaling roughly $21 billion, as estimated by the money invested by his victims. If the promised returns are added, the losses amount to $64.8 billion, but a New York court dismissed this estimation method during the Madoff trial.
The scheme is named after Charles Ponzi who became notorious for using the technique in early 1920. Ponzi did not invent the scheme (for example Charles Dickens' 1857 novel Little Dorrit described such a scheme decades before Ponzi was born), but his operation took in so much money that it was the first to become known throughout the United States. Ponzi's original scheme was based on the arbitrage of international reply coupons for postage stamps; however, he soon diverted investors' money to support payments to earlier investors and himself.
Knowingly entering a Ponzi scheme, even at the last round of the scheme, can be rational economically if there is a reasonable expectation that government or other person or organisation will bail out those participating in the scheme.