I am writing to address a critical aspect of interest group-based advertising concerning the interestGroupBuyers field in the ad auction process. This issue centers around the matching efficiency between a user's stored interest groups and the DSPs included in the interestGroupBuyers list by the seller (typically a publisher or SSP).

Core Concerns

Matching Efficiency:

There seems to be a potential inefficiency when there is a mismatch between the user's browser-stored interest groups and the DSPs listed in the interestGroupBuyers. This situation is akin to a "high cache miss" scenario where the system fails to find a relevant match, leading to inefficiency in ad auctions.

Single Entity Manipulation:

The current framework allows both the seller and buyer sides to manipulate which DSPs are included in the interestGroupBuyers list. While this can optimize ad relevance, it raises questions about fairness and the potential for market distortion.

Discussion Points

How are Others Addressing This Issue?

Are there existing strategies or solutions that have been effectively addressing the efficiency concern in matching interest groups with interestGroupBuyers?
What best practices can be adopted to enhance the matching process while maintaining user privacy?

Appropriateness of Single Entity Control:

Is it appropriate for a single entity (seller or buyer) to have significant control over the composition of interestGroupBuyers?
What are the potential risks of this control in terms of market fairness and competition?

Alternative Models or Suggestions:

Can alternative models or mechanisms balance efficiency, fairness, and privacy more effectively?
Can a more dynamic, real-time system for populating interestGroupBuyers be considered?

Impact on Smaller Players:

How does this system impact smaller publishers or DSPs in terms of participation and competitiveness in the ad auction ecosystem?

I am seeking the group's insights, experiences, and suggestions on this matter.
Collaborative discussion can lead to a better understanding of these challenges and the exploration of potential solutions. Any shared experiences, data, or innovative approaches to similar issues would be highly valuable.