---
id: "prereq-aggregator-theory"
type: "prereq"
source_timestamps: ["§ Lessons from Food and Travel Aggregators"]
tags: ["business-strategy", "platform-economics"]
related: ["concept-aggregator-economics"]
reason: "Crucial for understanding the historical parallel and the urgency of the 'Retailer's Dilemma'."
sources: ["geo"]
sourceVaultSlug: "hbr-seg-geo"
originDay: 3
articleStem: "hbr-nm-97-retailers-ai-shoppers"
sourceUrl: "https://hbr.org/2025/10/what-should-retailers-do-about-ai-shoppers"
sourceTitle: "What Should Retailers Do About AI Shoppers?"
---
# Understanding of Aggregator Theory

## Prerequisite — Understanding of Aggregator Theory

**Why it's needed:** Crucial for understanding the historical parallel and the urgency of the [[concept-retailers-prisoners-dilemma]].

The authors assume the reader understands how companies like [[entity-expedia]] and [[entity-doordash]] disrupted their industries by **commoditizing suppliers** and **owning the demand-generation layer**. Without this, the [[concept-aggregator-economics]] argument — that AI agents are the *new* aggregators — loses its force.

**Fast primer (enrichment):** Ben Thompson's **Aggregation Theory** holds that digital aggregators win by owning the customer relationship and discovery layer, commoditizing the suppliers beneath them. Two-sided-market economics (Rochet & Tirole; Evans & Schmalensee) explains platform pricing and the pivotal "who pays whom" question — directly relevant to "who pays the agent?"