Ivar Ekeland, mathematician and economist, was the chairman of the Université Paris-Dauphine;
Jean Charles Rochet, professor of economics at the Université de Genève, a specialist in banking economics, works at the Toulouse School of Economics.
Financial speculation is paradoxical in that it can be either beneficial or harmful. In small doses, it promotes risk-sharing in the economy and helps finance innovations. In large doses, it endangers not only the financial health of the “players,” but also periodically provokes very costly financial crises for society. Following the sub-prime crisis, the result of the banking sector’s freely-devised suicidal plans, the European commission came up with a tax on financial transactions (TTF). It is still filed away 10 years later.

The financial industry has made speculation accessible to everyone, counting on the “wisdom of the masses” to regulate markets. But at the same time, it tries hard to foresee the behavior of speculators, focusing on events that might crimp collective hysteria – seeking to profit from the “madness of the masses.” Since it is almost impossible to distinguish good and bad speculators, the authors propose a universal tax on all financial transactions, which could earn States 15 to 20 times more than the unlikely TTF.