The number of U.S. millionaires rose at a record rate of 17 percent in 2013 as surging equity markets and real estate lifted assets.

Houston and Dallas added to the ranks of the rich at faster rates than all major U.S. cities, helped by growing affluence from an energy boom, according to a Capgemini-RBC Wealth Management report released today. The number of Dallas-area millionaires increased 20 percent last year and their wealth rose 24 percent. Houston’s millionaire population expanded by 18 percent and its assets grew 22 percent.

New York saw the nation’s second-slowest increase in wealthy people, according to the report, which broke out the 12 biggest metropolitan areas based on high-net-worth population. The area’s millionaire and billionaire ranks expanded by 12 percent as their assets grew 16 percent, only outpacing Detroit.

“We’re seeing an expansion of wealth in the U.S. and a shift in where it is happening,” Bill Sullivan, global head of market intelligence for Capgemini Financial Services, said in an interview. Capgemini is a Paris-based consulting firm.

The number of people in the U.S. with at least $1 million in investable assets rose to 4 million, and they held $13.9 trillion in assets, according to the report. Stock-market gains, rising property valuations and wealth creation in industries such as energy and technology led to the acceleration in high- net-worth population and assets, John Taft, chief executive officer of RBC’s wealth-management unit in the U.S., said in an interview.

Wall Street

New York still has the largest number of wealthy people. Its high-net-worth population totaled about 894,000 last year, according to the report, compared with 330,000 for the next- biggest, Los Angeles.

Much of New York’s wealth is derived from Wall Street, which has trimmed jobs since the 2008 financial crisis while the technology and energy industries have grown in importance for the U.S. economy.

The Standard & Poor’s 500 index of U.S. stocks rose 30 percent in 2013, rallying for the fourth year in five. Home prices climbed 11 percent, according to the S&P/Case-Shiller national index.

Wealth expansion has been concentrated at the top in recent years, spurring debate about income inequality. The richest 10 percent of U.S. households saw income gains from 2010 to 2013, while median earnings fell for all other groups with wages stagnating, a report this month from the Federal Reserve showed.

Silicon Valley

Cities with concentrations of technology companies also saw jumps, Capgemini and RBC reported. The Seattle area, home to Microsoft Corp. and Amazon Inc., saw its high-net-worth population rise 17 percent last year. In San Jose, California, the largest city within Silicon Valley, the group expanded by 14 percent.

In Detroit, which filed for the largest U.S. municipal bankruptcy in July 2013, the millionaire count increased by 11 percent.

Wealthy Americans have the world’s highest allocation to stocks, at 33 percent of their investments, compared with an average of 22 percent for rich people outside the U.S., according to data from the firms. Asia was the fastest-growing region globally for millionaires and billionaires last year, fueled by China and Japan, according to a separate study by Capgemini and RBC.

Capgemini has conducted an annual report of global wealth since 1997. This study released today is based in part on a survey of 1,080 U.S. high-net-worth individuals in January and February.