DALLAS—The U.S. property/casualty insurance composite renewal rate dropped 5% in October, electronic insurance exchange MarketScout said.

“Rates had been progressively moderating for the last 21 months, trending from a reduction of minus 15% in January 2008 to minus 4% in September 2009,” Richard Kerr, chief executive officer of Dallas-based MarketScout, said in a Thursday statement. “The October rate reversal does not bode well for those looking forward to the end of the soft market.”

Mr. Kerr added that the reversal might be an anomaly, but added that insurance companies and intermediaries have been awaiting a month in which MarketScout would report rates as flat on a month-to-month comparison.

Commercial property insurance rates were down 5%, general liability was down 6%, while directors and officers liability rates were flat. By industry, manufacturing rates had the greatest decline at 6%, MarketScout said.