ComScore Wins Clients for Online-Ad Rating System
Posted: 5/17/2013  |  By: Suzanne Vranica | The Wall Street Journal
The battle between companies measuring the reach of online ads is heating up.

Ad-buying giants Starcom MediaVest Group and ZenithOptimedia said they have signed on to use comScore Inc.'s online advertising ratings system, dealing a blow to TV ratings leader Nielsen, which offers advertisers a comparable service.