This post was originaly written in French and translated below. In a financial context, diversifying risks means investing in a variety of assets, sectors, or geographic regions to avoid having the poor performance of a single investment significantly affect the overall portfolio. Diversification allows for risk reduction, or, in its mathematical formulation, the reduction of variance. But what happens when we encounter large risks, infinite variance? Or worse, infinite expectation? Extreme Risks and Infinite Expectation? Formalizing quantities related to random and uncertain quantities is …