This paper presents a method for calculating the spread for the generalized (B, S)-market in case of buying up shares. A brief description of the relevance of tasks, related to the calculation of market value of derivative of assets and concomitant calculations. Substantiate the use of Martingale ideology in studies of financial markets. Describes the essence of the generalized model (B, S)-market in case of buying up shares, as well as the principle of calculating of upper and lower value of the option-call European type.

Keywords: financial market, option, spread, model completeness, arbitration, financial strategy, the model of Cox-Ross-Rubinstein, financial liability, the martingale