Web portals are not the be all and end all that they used to be, but they still are valuable commodities to online marketers because of the traffic they drive. Google, for instance, sees over $7 billion in ad spends a year, while Yahoo gets $3.5 billion; AOL and Microsoft receive about $1 billion apiece.
eMarketer indicates that users still use main destination sites as much as they did five years ago, and are likely to continue doing so for at least the next few years. The over $13 billion in ad spend for top portals is over half the ad dollars for the whole Internet ($23.5 billion).
Source: Ad Week {link no longer active}
