The number of U.S. households with a net worth of more than $5 million, excluding their primary residence, surged 23 percent to surpass one million for the first time in 2006, according to a survey released on Tuesday.
The survey by Chicago-based Spectrem Group found that the number of U.S. households with more than $5 million rose from 930,000 in 2005. In 1996, there were only 250,000 U.S. households in the "ultra-rich" category, Spectrem said.