Many millionaires no longer enjoy doing their own investing and would like to hand over more of the task to their advisors, say two new studies by Spectrem Group.

Only 47% of millionaires, defined as those with a net worth of $1 million to $5 million in assets not including their primary residence, say they still want to be actively involved in the day-to-day management of their investments, which represents a substantial decline from the 65% that expressed the desire in 2010 and 69% in 2009.

For ultra-high-net-worth investors, those with a net worth of $5 million to $25 million, the results are similar. Only half want to be actively involved now, compared to 63% in 2010 and 67% in 2009.

Spectrem, a consulting firm specializing in the affluent and retirement markets, conducted the study of 1,484 households with a net worth of $1 million (not counting the primary residence) to $5 million, and 649 households with $5 million to $25 million.

The number of wealthy who say they actively enjoy doing their own investing declined to 45% in 2011 from 64% in 2009 and for the ultra high net worth the percentage dropped to 54% in 2011 from 63% in 2009.

Millionaire investors ages 65 and up are the more likely to be hands-on in the daily management of their investments, but even in this age group, interest has declined. Half now say they like to be actively involved, down from 68% in 2010.

"Wealthy Americans may simply be experiencing investor fatigue, prompting them to pull back and allow their advisors to take the lead in managing their assets," said George H. Walper Jr., Spectrem Group president. This was after "they underwent a period of intense vigilance and participation during the financial crisis."

During the crisis, millionaire investors may have been shaken by the loss of their net worth and felt they needed to take a more active role in their money management, Spectrem said. Millionaire households saw their assets decline 30% during the economic downturn. Nearly one-fifth (17%) of millionaires absorbed declines greater than 40%.

-Karen DeMasters