A system and method for optimizing advertisements. To maximize revenue, a plurality of ad networks are tiered based on their pricing data, and in one embodiment, their cost per thousand impressions (CPM). Each tier includes a pricing data range. Periodically, the system may increase and decrease frequency caps for the ad networks to adjust the ad networks in the tiers. Frequency caps may be increased for an ad network when the CPM for the ad network is above the CPM range for the ad network's tier. The frequency caps may be decreased for the ad network when the CPM for the ad network is below the CPM range for the ad network's tier. For each ad network request received, the system traverses through the tiers of the plurality of ad networks for an ad network that is capable of serving an ad based on the ad network's frequency cap.