Affluent Americans now have more assets in IRAs than in employer-sponsored retirement plans, according to a report by Cogent Research.

Cogent's survey of 4,000 people with at least $100,000 in investible assets found that participation in both types of retirement plans have dropped since 2006. But the rate of decline has been more dramatic in workplace-based retirement plans such as 401(k) and 403(b) accounts.

Specifically, IRA ownership has slipped 5% versus the 23% drop in workplace-based plans. Overall, the proportion of assets held in IRAs (31%) topped the proportion held in employer-sponsored plans (25%) for the first time since Cogent began tracking investor allocations.

"The good news here is that while many Americans are losing access to 401(k) plans as a result of job separation, choosing to bypass their 401(k)s or simply retiring, they are making smart decisions regarding where to move their money--namely, putting it in an IRA." said Meredith Lloyd Rice, Cogent senior research director and author of the study.

According to Cogent, seven leading brokerage firms during the past year have increased the average proportion of primary client assets in IRAs by more than 20%. Those companies are ING, Raymond James, USAA, Merrill Lynch, Vanguard, Fidelity, and Wells Fargo Advisors/Wachovia.

The report, 2010 Investor Assets in Motion: IRA & Retirement Marketplace Opportunities, will be released next week.