The research by accounting and covered 600 public companies with annual revenues between $25 million and $1 billion, and is based on proxy statements filed between May 15, 2010, and May 15, 2011.

"CEOs have always earned significantly more than other executives," Randy Ramirez, a senior director in BDO's Compensation and Benefits Practice, said, "but we have seen an even greater divide in recent years due to an increase in CEO pay leverage tied to the performance of their company's equity."

He added, "We expect CFO pay to start catching up within the next few years as the emphasis on pay-for-performance trickles down to other top executives."

BDO also publishes the that includes Board of Director compensation for the same 600 public companies.