The number of US households with a net worth of at least $1 million - not including primary residence (NIPR) – continued to spring back alongside the stock markets in 2011.

The number of US households with a net worth of at least $1 million - not including primary residence (NIPR) – continued to spring back alongside the stock markets last year, rising by 200,000 to 8.6 million, according to the Affluent Market Insights 2012 report by Spectrem Group.

The report demonstrates that the millionaire population has grown for three consecutive years, notwithstanding the 27 per cent decline in millionaire households to 6.7 million in 2008. However, the overall millionaire population remains below the pre-recession high in 2007 of 9.2 million.

This year’s set of results also show that the ranks of individuals with at least $5 million or more rose to 1.078 million from 1.061 million. Meanwhile, those with at least $25 million or more grew to 107,000 from 105,000.

The number of affluent investors also swelled last year: those with at least $100,000 reached 36.7 million in number, from 36.2 million a year earlier, while those with $500,000 or more climbed to 13.8 million from 13.5 million.

"Like unemployment, housing is a bellwether for investor optimism"

But despite their expanding portfolios, wealthy investors “remain worried about the future,” the survey uncovered. "Even if they are not directly impacted, continuing high unemployment and the depressed housing market are bedeviling wealthy investors," said George Walper, president of Spectrem Group.

"Investor optimism has climbed from negative in April 2011 to neutral in February 2012, according to our monthly Spectrem Affluent Investor Confidence Index, but investor outlook won't significantly improve until unemployment falls significantly lower,” he added.

Although wealthy individuals have “substantial assets” alongside their primary residence, their homes remain an “important investment,” Walper explained.

Overall, primary residences comprise 29 per cent of total assets among the mass affluent ($100,000 - $999,999 NIPR), a figure which stands at 16 per cent for the millionaire segment ($1 million - $5 million NIPR) and 9 per cent of total assets for UHNW individuals ($5 million plus NIPR).

The report is based on surveys with 12,519 affluent investors conducted throughout 2011.