The reduction is higher (i) for firms that are more upstream, (ii) when the degree of substitution is higher, (iii)when the number of substitutable products is higher, (iv)when the demand soft products are more correlated, and (v) when the degree of information sharing is higher. Our results suggest that firms, especially those that are upstream in the supply chain,may face a significant risk of over-estimating the value of information sharing if they ignore substitution, demand correlation, and partial information sharing effects