Reid Hoffman, LinkedIn's founder and chairman, now has a stake worth $1.8bn in a company that made profits of just over $2m in the first quarter of the year. While anyone can create a profile on the site for free, LinkedIn says that half of its $93.9m of first-quarter sales came from the subscription services it offers recruitment companies who use the site to help match candidates to jobs. About 30pc of the company's revenues were generated from advertising.