This excerpt taken from the WBMD 10-K filed Mar 16, 2006.
We may not be able to attract visitors to our Web sites on a consistent basis, which could have a material adverse effect on our results of operations
Since users of our public portals may be attracted to The WebMD Health Network as a result of a specific condition or for a specific purpose, it is difficult for us to predict the rate at which users will return to the public portals. Further, users of The WebMD Health Network have numerous other online and offline sources of healthcare information services, and some users may visit The WebMD Health Network as a result of our existing third party relationships. If one or more of these third parties engages in conduct that negatively affects users of those third party Web sites, users that come to The WebMD Health Network through these third party Web sites may decrease.
Because we generate revenue by, among other things, selling sponsorships of specific pages, sections or events on The WebMD Health Network for healthcare providers and consumers and related e-newsletters, a decline in user traffic levels or a reduction in the number of pages viewed by users could cause our revenue to decrease and could have a material adverse effect on our results of operations.