This is a bit complex, but read the following. It might not be a person going around doing this.
Agora
An Agora facilitates exchange between buyers and sellers. Prices are "discovered" through real-time, on-the-spot negotiations, whether through one-to-one haggling or through multi-party auctions and exchanges. A wide variety of goods and services are available, and access to the marketplace is relatively easy for those whose products or services fit the category. The highest profile examples are eBay and Priceline.
Aggregation
In an Aggregation B-web, one company usually leads in hierarchical fashion, positioning itself as a value-adding intermediary between producers and customers. The lead aggregator takes responsibility for value selection and fulfillment, pricing, and market segmentation. E*Trade has aggregated many companies to create a virtual stock broker, charging one-tenth the fees of a regular broker.
Historically, the brokerage industry depended on vertically integrated full-service providers. E*Trade disaggregates this value proposition into its elements and then through partners reaggregates it on the Net. These partners include stock quote services (Reuters, Quote.com), news (Reuters, PR Newswire, Businesswire), proprietary issues (Robertson, Stephens), research (Briefing.com, InvesTools), market trends and projections (Baseline Financial Services), to name but a few. These services give E*Trade's customers far more timely information and value than any traditional broker.