The difficulties of retirement income planning and asset decumulation will prompt many U.S. investors to consolidate assets with a single advisor, TowerGroup Inc. predicts.

Some financial services institutions will gain when investors consolidate assets, but others will lose, according to TowerGroup, Needham, Mass.

Individuals have about $9 trillion in retirement assets, and business owners could liquidate another $10 trillion in assets over the next decade, TowerGroup researchers estimate.

Financial services firms have to be prepared to help clients who move up into the high-net-worth category, then fall down into the mass market as their nest eggs empty, the researchers write.