Level 3 Aggregators: Zero Supply Costs: Level 3 Aggregators do not own their supply and incur no supplier acquisition costs (either in terms of attracting suppliers or on-boarding them). Google is the prototypical Level 3 Aggregator: suppliers (that is, websites) are not only accessible by Google by default, but in fact actively make themselves mor... See more

Market-making is certainly a characteristic of Aggregators; Google, for example, is a one-stop shop for users, advertisers, and content suppliers. What makes Aggregators unique, though, is their infinite scalability, driven by the effectively zero marginal and transactional costs necessary to serve one more user, advertiser, or supplier.