Marsh said it expects further commercial insurance rate decreases in 2011 as intense competition and overabundance of capacity continue to define the marketplace.

In a new report, Marsh said the market is likely to remain stable into 2011 "barring an unforeseen market-changing event."

As an example of the tough conditions, the Marsh report said that despite an estimated $18 billion in worldwide insured catastrophe losses in the first two quarters of 2010, property rates for domestic and global businesses purchasing insurance in the U.S. typically declined 5 to 10 percent in the third quarter.

"Barring some unforeseen event, the property market's abundance of capacity will likely impel insurers to further decrease rates into 2011 in order to maintain market share," the report said.

Specifically, the report said that property rates declined an average of 6.1 percent; general liability rates declined an average of 6.7 percent; workers' compensation rates declined an average of 5.3 percent; auto liability rates declined an average of 0.1 percent; and directors & officers liability rates declined an average of 8.7 percent.

In the D&O area, the report warned underwriters of the potential impact of provisions in the recently enacted Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010.

The report said that while the full impact of the legislation will not be known for some time, Section 922 of the Act provides new incentives to whistleblowers, including substantial "bounties" in proceedings where the Securities and Exchange Commission (SEC) collects more than $1 million in fines or penalties.

"These new provisions could lead to a wave of employee whistle blowing that could result in significant regulatory activity and follow-on civil litigation," the report said.

In the primary casualty area, which comprises workers' compensation, general liability and automobile liability, the market remains "largely a "buyer's market," the report said.

Primary casualty rates trended downward on average across all lines of business through the third quarter, the report said.

The report is based on data from Marsh's Global Benchmarking Portal and reflects transactions brokered by Marsh through the end of the third quarter.