quadratic utility \begin{equation} U(x) = \lambda x - x^{2} \end{equation} where, \lambda>0 controls risk aversion: as risk increases, utility increases concavely, then eventually utility falls exponential utility \begin{equation} U(x) = 1 - e^{-\lambda x} \end{equation} where \lambda >0 controls risk aversion. This is usually not plausible as utility because people’s utility doesn’t grow exponentially ever power utility see power utility