On the casualty side, pricing is decreasing in the low single digits and is expected to remain flat. However, carriers with difficult risks may pursue increases where they perceive limited competition.

Like property, insureds are maintaining limits and the vast majority have not changed deductible or retention levels.

Carriers are exerting some underwriting discipline when it comes to emerging risks, but coverage enhancements exist, Aon said.

Discussing directors and officers liability coverage, the report said rates were down an average of more than 15 percent in the first quarter and, like the other lines examined, insureds maintained limits.

Restrictions were placed around emerging risks, a practice that is expected to continue through this year.

Capacity rose close to 2 percent in the quarter and new entrants are expected, increasing capacity through the rest of the year.

Federal Securities Class Action suits were down 33 percent from the same period in 2009, with a total of 34 suits filed compared to 51 in 2009. That trend is expected to continue, Aon said.

"In the current pricing environment, there does not appear to be any real financial imperative for insureds to 'voluntarily' increase retentions," the report said. "Until the D&O market begins to tighten, we do not expect underwriters will have the leverage to increase retentions they deem inadequate. However, when the time does arrive, adjusting retention levels would offer insureds a mechanism to minimize price increases."