The MarketScout rating barometer measured an overall rate dip of 4 percent for September 2010 as well.

The October figures, MarketScout said, extend the "slow and steady moderation trend that began in August 2009."

For the last 14 months rate reductions have been very tight, measuring from minus 5 percent to minus 3 percent, according to the Dallas-based electronic insurance exchange.

In a statement released with the latest barometer figures by line and account size, Mr. Kerr speculated on market-turning events that would break the moderation trend. "A major catastrophe in excess of $100 billion could impact the market. Another factor that could ultimately increase rates is the lack of return capital providers have seen in their U.S. insurance portfolios."

He also noted that investments in some startup companies have not gone as well as expected. If fewer capital providers are willing to back startup insurers, then the constriction on the supply side (less capital) could ultimately drive rate hikes, he said.

But "absent a major catastrophe or reduction in capacity, the current rating environment may be the new normal," Mr. Kerr concluded.

MarketScout's summary of rate changes by coverage class shows that the largest rate declines in October came in the general liability line (5 percent), and the commercial property line (4 percent), while professional liability, D&O, fiduciary, crime and surety were less pronounced (in the 1-2 percent range.)

October declines for workers' compensation and commercial automobile were 2 percent and 3 percent.

While large accounts (with over $250,000 in premiums) continued to experienced the biggest rate cuts at 5 percent, small accounts only saw discounts of 2 percent in October.

Last year, the average rate decline for p&c coverages in October was 5 percent. A month before that, the average drop of 4 percent in September prompted Mr. Kerr to describe a "moderation trend" in the overall market.