The gap between the top U.S. asset managers and the bottom performers is widening.

Consultants at McKinsey & Company, New York, have published that conclusion in the firm’s fifth annual U.S. asset manager review.

There is now a 41% difference in operating margins between the top-third and bottom-third asset managers that McKinsey tracks, the consultants write.

The difference has grown dramatically over the past 3 years, and a growing number of U.S. assets managers now are earning margins under 20%, McKinsey consultants write.

Demand and prices for a number of established products fell by more than 10% in 2005 alone, the consultants report.