I dislike those estimates. Yahoo is the Nth highest-traffic site in the English speaking world, where N is probably < 100. It strains credulity to imagine that a site with that much traction truly has negative value.
Edit: [0] claims that Yahoo is the 6th most popular site on the web.
That's true of most sites in the English speaking world. If you remove the fuzziness of "probably", its true of all but 100.
> It strains credulity to imagine that a site with that much traction truly has negative value.
That only makes a little bit of sense if you flip the > to be a <.
But even then, traffic is a cost driver; its only worth something if you have an effective way of monetize it. "We lose money on every transaction, but make up for it in volume" is as much of a fallacy with web sites where the transactions are "visits" as it is for any other type of interaction.