It is true that theory can seem to diverge from the realities of markets, especially when a government, for example, implements restrictions on currency flows to protect its economy. Scene: an investor sees their sensitivity calculation, so precise in theory, hit the wall of an unexpected executive order. This state intervention, unpredictable by classical models, forces a rewriting of the scenario of equivalence, even if the mathematical proof is impeccable. The energy market in Europe, for example, has seen massive subsidies and price caps radically alter the expected behavior of actors.