“…Observe that the process H (n) (kT /n) M (n) (kT /n) , 0 ≤ k ≤ n is a martingale with respect toP ξ n and the filtration {F ξ k } n k=0 , thus (since the multinomial markets are complete) there exists π ′ n ∈ A ξ,n (x) such that V π ′ n (k) = H (n) (kT /n) M (n) (kT /n) , k ≤ n. We obtain that for any n there exists a stopping time σ n ∈ T ξ n which satisfies Finally, by using (4.13) for the process Φ(t) := (Y W (t) − H(t) M(t) ) + , (4.9) and (4.11)-(4.12) we obtain H ξ,n (k, l) = G( kT n , S ξ,n )I k<l + F ( lT n , S ξ,n )I l≤k , n ∈ N, 0 ≤ k, l ≤ n. The terms H W (t, s) and H ξ,n (k, l) are the payoff functions for the BS model and the n-step multinomial model, respectively. For game options the shortfall risk is defined by (see [5])…”