In this paper, we deal with the uncertainty of bidding for display advertising. Similar to the financial market trading, real-time bidding (RTB) based display advertising employs an auction mechanism to automate the impression level media buying; and running a campaign is no different than an investment of acquiring new customers in return for obtaining additional converted sales. Thus, how to optimally bid on an ad impression to drive the profit and return-on-investment becomes essential. However, the large randomness of the user behaviors and the cost uncertainty caused by the auction competition may result in a significant risk from the campaign performance estimation. In this paper, we explicitly model the uncertainty of user click-through rate estimation and auction competition to capture the risk. We borrow an idea from finance and derive the value at risk for each ad display opportunity. Our formulation results in two risk-aware bidding strategies that penalize risky ad impressions and focus more on the ones with higher expected return and lower risk. The empirical study on real-world data demonstrates the effectiveness of our proposed risk-aware bidding strategies: yielding profit gains of 15.4 in offline experiments and up to 17.5 in an online A B test on a commercial RTB platform over the widely applied bidding strategies.
Computational advertising is associated with a certain level of deficit risk, particularly for performance-driven campaigns as the goal is to acquire new users and gain more sales from them. The risk comes from the dynamics of the market and the user online behaviors @cite_38 . The authors in @cite_36 proposed to measure campaign-level risk and return in a special case of arbitrage between CPM and CPA. Compared to @cite_36 , our work focuses on single campaign optimization, and our risk is modeled from the uncertainty of user response and market competition at impression-level. Generally, our work borrows the concept of value at risk from finance to derive risk-aware bidding strategies intending to reasonably allocate budget between uncertain impressions and confident impressions and achieve a campaign-level profit gain, which is unlike in finance where risk control is only for balancing return and risk at item-level (impression-level in RTB).
@cite_36 @cite_38
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We study and formulate arbitrage in display advertising. Real-Time Bidding (RTB) mimics stock spot exchanges and utilises computers to algorithmically buy display ads per impression via a real-time auction. Despite the new automation, the ad markets are still informationally inefficient due to the heavily fragmented marketplaces. Two display impressions with similar or identical effectiveness (e.g., measured by conversion or click-through rates for a targeted audience) may sell for quite different prices at different market segments or pricing schemes. In this paper, we propose a novel data mining paradigm called Statistical Arbitrage Mining (SAM) focusing on mining and exploiting price discrepancies between two pricing schemes. In essence, our SAMer is a meta-bidder that hedges advertisers' risk between CPA (cost per action)-based campaigns and CPM (cost per mille impressions)-based ad inventories; it statistically assesses the potential profit and cost for an incoming CPM bid request against a portfolio of CPA campaigns based on the estimated conversion rate, bid landscape and other statistics learned from historical data. In SAM, (i) functional optimisation is utilised to seek for optimal bidding to maximise the expected arbitrage net profit, and (ii) a portfolio-based risk management solution is leveraged to reallocate bid volume and budget across the set of campaigns to make a risk and return trade-off. We propose to jointly optimise both components in an EM fashion with high efficiency to help the meta-bidder successfully catch the transient statistical arbitrage opportunities in RTB. Both the offline experiments on a real-world large-scale dataset and online A B tests on a commercial platform demonstrate the effectiveness of our proposed solution in exploiting arbitrage in various model settings and market environments. Many online advertising slots are sold through bidding mechanisms by publishers and search engines. Highly affected by the dual force of supply and demand, the prices of advertising slots vary significantly over time. This then influences the businesses whose major revenues are driven by online advertising, particularly for publishers and search engines. To address the problem, we propose to sell the future advertising slots via option contracts (also called ad options). The ad option can give its buyer the right to buy the future advertising slots at a prefixed price. The pricing model of ad options is developed in order to reduce the volatility of the income of publishers or search engines. Our experimental results confirm the validity of ad options and the embedded risk management mechanisms.