Jerry Yang promised to overhaul Yahoo within his first 100 days after becoming Yahoo's CEO in July, yet an Adweek article says he was wrong to mark time that way, as the overhaul had already begun hundreds of days before Yang made his statement.

During Terry Semel's tenure, Yahoo started its expansion beyond a Web portal in order to become part of an online ad network. Semel used to hold up Yahoo's value as a portal, where the revenue can be generated by attracting traffic. However, when he found it was obviously not enough, Yahoo started to switch to online advertising. The company purchased Right Media late last year, and bought BlueLithium earlier this month, both of which have bolstered the company's online ad model.

However, does Yahoo have to cast off its portal-centric qualities which, according to Semel, made the company so valuable? Todd Teresi, SVP of display marketplaces at Yahoo, tells Adweek that “the portal is still key.”

Operating a portal enables Yahoo to collect and store behavioral data about consumers, which can ultimately be used to target them. For example, a visitor to Yahoo's hybrid cars' section, later on can be targeted with a hybrid car ad.

“Without that ability to target people, delivering relevant ads isn't possible,” Teresi said.