The number of high-net-worth (HNW) individuals in the U.S. with at least $1 million in investible assets fell 18.5% last year, according to the consulting company Capgemini.

But among the 10 markets with the largest high-net-worth populations, that rate declined less, at 15.7%. As defined by Paris-based Capgemini's 2008 U.S Metro Wealth Index, the top ten HNW markets are New York, Los Angeles, Chicago, Washington, San Francisco, Boston, Philadelphia, Detroit, San Jose and Houston.

Among them, New York registered the smallest decline at 13.6%, followed by the two Bay Area entrants--San Jose (-13.9%) and San Francisco (-15.3%). Houston (-21.1%) was the only metropolitan area among the HNW top 10 with a drop exceeding 20%.

Among the largest metro areas nationwide, the sharpest drops in HNW folks took place in such markets as Orlando (-42%), Las Vegas (-38%) and Phoenix (-34%). All three experienced rapid gains in HNW individuals in prior years, but plunging real estate values and hard times in core regional industries, such as tourism, during the recession put a serious dent in those numbers.

Capgemini's wealth index, which examines wealth dynamics of different markets, found that more established HNW markets tend to have more diversified economies, which helped cushion the blow somewhat last year and resulted in smaller declines in HNW populations.

According to Capgemini, the U.S. remains the global leader in HNW individuals, and its total is more than second-place Japan and third-place Germany combined.

But the moral of the story, says Capgemini, is that many HNW people have lost trust and confidence in their financial advisor or wealth management firm. And that's the top reason why they might withdraw some or all of their assets from their advisors.

As a result, the company says there's a lot of money in flux as clients decide where and with whom to invest their money.