A shadow price is a process <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$${\widetilde{S}}$$</EquationSource> </InlineEquation> lying within the bid/ask prices <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$${\underline{S},\overline{S}}$$</EquationSource> </InlineEquation> of a market with proportional transaction costs, such that maximizing expected utility from consumption in the frictionless market with price process <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$${\widetilde{S}}$$</EquationSource> </InlineEquation> leads...</equationsource></inlineequation></equationsource></inlineequation></equationsource></inlineequation>