Large liquidity expansion of super-hedging costs

We consider a financial market with liquidity cost as in Çetin, Jarrow and Protter [3] where the supply function S(s, ν) depends on a parameter ε ≥ 0 with S(s, ν) = s corresponding to the perfect liquid situation. Using the PDE characterization of Çetin, Soner and Touzi [6] of the super-hedging cost of an option written on such a stock, we provide a Taylor expansion of the super-hedging cost in powers of ε. In particular, we explicitly compute the first term in the expansion for a European Call option and give bounds for the order of the expansion for a European Digital Option.