There are, of course, millions of Web sites, and in theory they provide a diverse spectrum of viewpoints, which is one rationale for restrictions against any one company owning too many news outlets. In practice, however, almost all this diversity is ignored. Users may be able to choose from millions of sites, but most go to only a few.
This isn't an accident or the result of savvy branding. It's because Internet traffic follows a winner-take-all pattern that is much more ruthless than people realize.
Relying on links and search engines, most people are directed to a few very successful sites; the rest remain invisible to the majority of users. The result is that there's an even greater media concentration online than in the offline world.
Our research on online political communities -- analyzing three million pages on issues like abortion and capital punishment -- shows a staggering degree of consolidation. For instance, although there are more than 13,000 Web pages on the subject of gun control, two-thirds of all hyperlinks point to the 10 most popular sites. In the case of capital punishment, the top 10 sites receive 63 percent of the total number of links on the topic. In every category of content we examined, more than half the Web sites have only a single link to them.
The number of links to a Web site is correlated with the amount of traffic the site receives, since it determines a site's visibility on the open Internet: popular sites continue to acquire more links, making their predominance even more pronounced. The top 20 online news sites are owned by 16 large media companies. The top five sites get more traffic than the other 15 combined.
The Web, undoubtedly, has changed the media landscape. But it is not the first technology to do so. Current news media ownership regulations were themselves a farsighted attempt to come to grips with a new technology: television. The policies, which date back to the 1940's, have proved largely successful in ensuring the degree of diversity that a healthy democracy requires.
While regulation must remain flexible to account for technological change, the Internet shouldn't be invoked to justify diluting existing safeguards. In praising the Internet, let us hope that current regulators don't misunderstand it.
Matthew Hindman and Kenneth Neil Cukier are fellows at the National Center for Digital Government at Harvard University.