A proportionality (negative or positive) of the risk of a position to its size. A positive homogeneity is one of a set of conditions/ axioms that a risk measure has to satisfy to be coherent (coherent risk measure): the other conditions (axioms) being, subadditivity, monotonicity and translation invariance. A positive homogeneity implies the risk of a position is proportional to its size.
In general, homogeneity implies the existence of a level of similarity among risk factors in a system (such as financial institutions and other market players in the financial sector).
