Financial speculation must be taxed.

Summary "The financial industry has made speculation accessible to all, counting on the "wisdom of crowds" to regulate the markets. But this wisdom is not always forthcoming: from the tulip mania in Holland in 1637 to the subprime crisis of 2008, there are many examples of speculative bubbles bursting! The fascinating history of speculation, recounted here, is not short of surprises. Among them, the most paradoxical is that financial speculation can be both beneficial and harmful. In small doses, it improves risk sharing in the economy and contributes to the financing of innovations. In large doses, it causes financial crises that are very costly for society. Just as we limit speed on the roads to avoid accidents, we must limit financial speculation, and to do this we must tax it. Following the subprime crisis, which caused a global recession, the European Commission had planned to introduce a tax on certain financial transactions deemed speculative. But it is very difficult to distinguish between speculative and non-speculative transactions. The authors propose here a solution applicable to all transactions. It would have a very small impact on daily life, but would hit the most speculative transactions hard. The remedy to the excesses of financial speculation exists. It remains to apply it urgently".