The survey, from Marketing Services Financial Intelligence, is based on the ratios of debt, and intangible assets such as goodwill, to shareholders' funds.
The research aimed to find out how exposed companies might be to write-downs in the value of acquisitions.
Bob Willott, who published the survey, said a ratio of debt to shareholders' funds much above 2:l "should set alarm bells ringing unless a plausible explanation is available".
In the case of Aegis, the owner of Carat, Vizeum and Posterscope, Willott attributes the high ratio of 4:1 to past acquisitions. "Exposure to a decline in the value of its acquisitions remains a significant risk," he warned.