New York—IBM Corp. is the most effective brand in North America, and Ogilvy & Mather North America, New York, is the most effective agency network, according to the 2012 North American Effie Effectiveness Index. The index was released at the 44th annual Effie Awards Thursday.

The Effie Effectiveness Index ranks marketers and agencies based on an analysis of finalist and winner data from 40 worldwide Effie competitions held between June 2010 and June 2011.

The top advertiser is Procter & Gamble Co., and the top agency holding company is WPP, according to the index.

Also, Ogilvy & Mather New York is the most effective individual agency office, and McKinney, Durham, N.C., is the most effective independent ad agency.