I get the same benefit. Once you have a million people there on either side, it's incredibly attractive because the seller knows that he is going to find a buyer and the buyer knows he is going to be able to find what he wants. Horizontal, or functional, hubs can perform a process or function across several different industries. Hubs can use different procedures to arbitrate between buyers and sellers. The common catalog model provides a fixed-price listing of products from one or several suppliers.
Sellers can put items up for auction, while buyers submit bids for the products.
In the exchange model, the hub collects bids from the suppliers of a product and submits the bids to the buyers. The barter model lets buyers and sellers exchange assets other than money. One is that you need significant domain expertise and relationships. You can't go set up a paper exchange without knowing something about paper or having a relationship with the major manufacturers and the major buyers of paper. The decision, he said, should be based on the dynamics of each specific industry.