U.S. residents ended 2006 with $4.2 trillion in individual retirement account assets, up about 16% from the 2005 total.

Researchers at the Employee Benefit Research Institute, Washington have published that figure in an analysis of IRA asset data from a variety of sources.

Life insurers increased their IRA asset total 5%, to $323 billion, and they continued to manage about 8% of IRA assets.

Mutual funds and brokers selling self-directed IRA accounts increased their IRA asset total 18%, to $3.7 trillion.