The Portal Marketing report analyzes the revenue and traffic figures at the leading portal sites – and accesses their impact on Internet advertising as a whole.

eMarketer estimates that net US ad revenues at Yahoo!, AOL, MSN and Google represented 57.4% of the total Internet ad spend in 2006.

Even if Google is not included among the portals, eMarketer projects that a third of online ad spending in 2007 will come through the other three sites.

Voy a buscar datos a cerca de los portales donde más se invierte en españa, me imagino que algunos coincidiran pero me gustaria ver como se reparte el pastel.