The number of high net worth individuals within the top ten US metropolitan statistical areas increased in 2010 by 7.3 per cent, with nearly all MSAs surpassing their 2007 pre-crisis levels, according to the Capgemini 2011 US Metro Wealth Index.

New York is at the number one spot with 15,489,000 HNW individuals, up 7.9 per cent from 2008-2009, followed by Los Angeles, with 10,250,000, and then Chicago, with 7,621,000. HNW individuals are defined here as those with at least $1 million in investible assets. 

Houston had the highest total growth rate at 9.6 per cent, allowing it to overtake Detroit at the number eight position. This is the second consecutive time Houston has gone up the ranks, the index noted. It listed tenth in 2008.

"In addition to one of the lowest unemployment rates among the 10 MSAs, Houston's economy has significant exposure to the oil and gas industry, which may have contributed to the growth in Houston's HNWI population," said William Sullivan, the head of global market intelligence for Capgemini Financial Services. 

The rise in US equity and commodity markets has helped many investors see growth in the value of their investments, the index said. 

"HNWIs, not just in these MSAs, but globally, are taking on more calculated investment risks and shifting assets into what we consider more aggressive asset classes in a continued effort to recoup some of the losses they faced as a result of the financial crisis," added Sullivan. 

The other MSAs in the top ten list are Washington DC, San Francisco, Philadelphia, Boston, and San Jose.