Abstract: Various technologies described herein pertain to smoothing budgets of advertisers in online advertising. Information that indicates respective budgets of advertisers for online advertising during a time period and bids for auctions during the time period from the advertisers can be received. Moreover, a determination concerning whether to either throttle an advertiser from an auction or permit the advertiser to participate in the auction can be effectuated for each of the auctions during the time period and for each of the advertisers. The determination satisfies equilibrium conditions between the advertisers based on the respective budgets of the advertisers and the bids of the auctions. Moreover, winning bids for the auctions during the time period are determined. The winning bids can be determined from the bids of the advertisers respectively permitted to participate in each of the auctions.