NEW YORK: Social media adoption rates have discernibly "levelled off" among the biggest brand owners in the US during the last year, a new study has suggested.

The Center for Marketing Research at the University of Massachusetts Dartmouth and the Society for New Communications Research monitored the social media activity of firms in the Fortune 500, which lists the top American corporations by annual revenue.

"The adoption of blogs, Twitter and Facebook in the 2011 F500 appears to have levelled off with no significant change in the past year," their report said.

More specifically, some 289 of the organisations assessed currently boast a presence on Facebook, equivalent to an uptake of 58%. This total had only grown modestly, from 56%, in the last 12 months.

While 48% of the top 200 companies featuring in the Fortune 500 ran Facebook pages, figures fell to 35% for those operators making up the bottom 200 members of this group.

Coca-Cola was the brand with the highest number of fans, logging 32.3m "likes", bettering Starbucks with 24.1m, McDonald's with 9.4m and Wal-Mart with 7.1m.

Twitter actually enjoyed a stronger rate of adoption than Facebook, as 308 firms had accounts on the microblogging property, equating to a penetration of 62%, measured against 60% in 2010.

Google attracted the most followers here, on 3.3m, ahead of Whole Foods on 2m and Starbucks on 1.6m. In all, 49% of the top 200 are now leveraging Twitter, falling to 34% of the bottom 200.

Moreover, 156 of the 500 corporations tracked have not established themselves on Twitter or Facebook, according to the analysis.

Elsewhere, 114 companies possessed public-facing blogs which had been updated in the last year. This represented 23% of relevant organisations, exactly matching the score posted in 2010.

Wal-Mart are Exxon were some major industry players communicating with customers in such a way, but Fannie Mae, Chevron and Conoco Philips are all yet to pursue the same approach.

"Given that the F500 are the titans of American business, we may be seeing the slowdown in business adoption of social media. At the very least, this group appears to have slowed or stopped its adoption of the three most prominent tools - blogging, Facebook and Twitter," the study argued.

Data sourced from University of Massachusetts Dartmouth; additional content by Warc staff