Facebook is testing a tool it claims will help marketers track the return on investment from advertising campaigns on the social networking platform.

The 1 billion user-strong social network has been under ever greater pressure from marketers to prove the ROI of its advertising, and it claims the tool has been "highly requested.”

Facebook went public in May, and its stock price plummeted shortly thereafter. Since then, it has worked to prove the value of advertising on the social network. ...