Motivated by the observation
that the gain-loss criterion, while offering economically meaningful prices of contingent claims,
is sensitive to the reference measure governing the underlying stock price process (a situation
referred to as ambiguity of measure), we propose a gain-loss pricing model robust to shifts in the reference measure.
Using a dual representation property of polyhedral risk measures
we obtain a one-step, gain-loss criterion based theorem of
asset pricing under ambiguity of measure, and illustrate its use.