The growth rate in households with net wealth of $25 million and above decelerated sharply in 2018.

The number of US millionaires rose to 11.8 million during 2018 even while equity markets stuttered, with segments from high net worth to ultra-high net worth rising, according to Spectrem Group, a research firm operating in Chicago.

But while the data has been seized on by some news services, pointing out that there are now more US millionaires than the entire population of Sweden, the Spectrem report struck a cautionary note. The growth of people with a net worth of over $25 million, rising by 1,000 to 173,000 households in 2018, indicated that the pace of growth was slowing. The 2018 growth rate is down from the rise of 16,000 in 2017.

The rise means that there has been an upward trend for the 10th straight year, the organization said in its Market Insights 2019 report. 

In 2018, there were 31.2 million mass affluent households with a net worth of between $100,000 and $1.0 million, rising by 200,000 households from 2017. 

The number of millionaires, defined in the report as those with a net worth of between $1.0 million and $5.0 million, climbed to 10.23 million, rising by 2.5 per cent on a year earlier.

At the UHNW end of the scale, defined as those with a net worth between $5 million and $25 million, there were 1,397,000 households in 2018, rising by 47,000 from the level reported in 2017.

“In 2018, the increase in the number of US wealthy households slowed as a result of weakening global economic growth and a contentious US political environment,” Spectrem Group president George H Walper, said. “While net household wealth among affluent investors continued to increase last year, it did not match the pace it had experienced in prior years. Despite this, the total number of households in the upper wealth segments in the US has nearly doubled since the onset of the global financial crisis in 2008.”

(Editor's note: A number of reports, from organizations as varied as Capgemini, Boston Consulting Group and Credit Suisse are due to come out later this year to track what has happened to the number of wealthy persons around the world. It will be surprising if last year's fall in global stock market indices haven't had an impact.)