US wealth adviser Elmer Rich III, an early convert to the value of social media in transactions with clients, has started to warn them off it.

In a widely distributed e-mail Rich wrote: "We are forbidding our clients to use social media, including LinkedIn. The legal and reputation risks are just too high and getting worse. The core problem is no policing, so anyone can go in and say anything about you and your firm and it is memorialised on the web forever...Stay off and stay away."