Let us briefly sketch the classical hedging problem in a stochastic model of financial market. The goal of an investor having an initial capital x ≥ 0 is to hedge dynamically a given random variable H which represents the payoff of a financial contract at some future date T > 0. He is looking for a trading strategy π such that the related portfolio wealth

at T exceeds H almost surely, i.e.
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(1.1)
A strategy π satisfying (1.1) is called a hedging strategy for H and it is well known that it exists if x is greater than the price of H. In the opposite case each trading strategy is able to hedge the claim at most partially, i.e.
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, and hence generates the shortfall
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which is strictly positive with positive probability. The related shortfall risk which appears in that case should be minimized to protect the investor against the loss resulting from a low value of the portfolio.
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