NEW YORK—Edelman became the first $600 million public relations firm in 2011, consolidating its hold on the number one spot in the Holmes Report Global Ranking of the world’s 250 largest public relations firms, ahead of Weber Shandwick and Fleishman-Hillard. Edelman’s 15.7 percent growth in 2011 was the strongest of any of the top 10 firms.

Among the giant multinational agencies, Edelman, Weber Shandwick, Ogilvy Public Relations and MSLGroup enjoyed double-digit growth, but MSL was the only firm to move up the rankings as a result, leapfrogging Burson-Marsteller to become the fourth largest public relations firm in the world, thanks in large part to acquisitions such as Schwartz Communications in the United States.

MSLGroup's fee income total includes all revenues from acquisitions made during 2011, not just the revenues from the post-acquisition period. This formula was followed wherever possible to provide the most accurate snapshot of the group’s size and scope as of December 2011.

Fee income for nine of the top 10 firms is estimated by The Holmes Report based on published sources (including holding company revenues) and our own knowledge of the industry, with the majority of large holding companies continuing to use the Sarbanes-Oxley financial disclosure rules as an excuse not to publish numbers of individual businesses.

The two fastest-growing firms among the top 25 both benefited from mergers in 2011. As a result of its acquisition by French communications agency Public Systeme, Hopscotch leapt into the top 20, in part because much of the group’s digital and social media revenue meets The Holmes Report’s definition of public relations income. And the merger of UK financial PR firm Finsbury with Robinson Lerer Montgomery in the US (both owned by WPP) created a new top 25 business.

While more than half (13) of the top 25 firms are headquartered in the US, there is growing geographic diversity at the top, with firms from France and the UK being joined by leading German and Brazilian agencies.

Independent firms, meanwhile, continue to outperform the holding companies in terms of growth, with Edelman only the most prominent example. Overall, independent firms submitting information to the Holmes Report 250 experienced growth of better than 10 percent, compared to average growth of around 6 percent for the public relations operations of major holding companies.

Over the coming weeks, The Holmes Report will publish additional data, analysis and research into industry trends based on the information submitted to our 2012 Global Rankings. That information will be consolidated here at our dedicated Global Rankings microsite.