Before revision: Fat tails arise endogenously from modeling of price change based on  a quotient of arbitrarily correlated demand and supply (i.e., excess demand) whether or not jump discontinuities are present.
After revision: We show that the quotient of Levy processes of jump-diffusion type has a fat-tailed distribution. An application is to price theory in economics. We show that fat tails arise endogenously from modeling of price change based on a quotient of arbitrarily correlated demand and supply (i.e., excess demand) whether or not jump discontinuities are present.