Soon, the bulk of web advertising space may be bought and sold on exchanges, just like commodities. Currently there are a number of exchanges run by small companies, but according to a recent article from The Wall Street Journal, Microsoft, Google and Yahoo! are beginning to explore the space.
Currently, web display ads usually get sold through sales people or an ad network, but there is generally a large amount of unsold inventory. This is where the exchange would come in, matching buyers and sellers to reduce unused space. The current problem is that with numerous exchanges and a lack of standards, there isn't enough critical mass to reach desired market liquidity (an asset's ability to be easily bought or sold without significant price fluctuation or loss of value).
Some industry insiders believe that exchanges could eventually process half of all online ads, once the market matures. While it is true that many high-profile Internet ad campaigns require human interaction, some say that this is only 10 percent of the market, and that the rest has the potential to be traded on an exchange.
Moving to an exchange system eventually will benefit both the buyers and the sellers. All of that inventory left unused (or sold at last-minute cheap rates) will have a home (and a market price)!