An improved system and method for pricing of overlapping impression pools of online advertisement impressions for advertising demand is provided. An inventory of online advertisement impressions may be grouped in impression pools according to attributes of the advertisement impressions and advertisers' requests for impressions targeting specific attributes may be received. An optimal price may be computed for each of the impression pools of the inventory of online advertisement impressions using dual values of an optimization program. The values of a dual variable for prices of impression pools on the supply constraints of an objective function for allocating the impression pools may be extracted and iteratively increased on those impression pools which have a dual value greater than the book rate value.