The combined wealth of the world’s richest people increased by more than 18% over the past year to $2.6 trillion, Forbes magazine said, as it released its worldwide billionaires list yesterday. The editor in chief, Steve Forbes, said it was an “extraordinary year” for the global economy.

The head of J.P. Morgan Private Bank in the Northeast, John Duffy, said emerging markets are playing a role in the growth of the ultra-wealthy class. “The world suddenly has 3 billion new capitalists,” he said, referring to populations in countries such as China, India, and Brazil. “Combine that with the incredible growth in capital and liquidity we’re seeing in those markets, and it’s no surprise that they’re growing at such an incredible pace.”

America is home to 371 of the 793 billionaires in the world, a rise from 341 a year ago. Forty-nine New Yorkers, or about 6% of the total list, made the cut. The wealthiest among them is Carl Icahn, the self-made 66-year-old investor who is worth $8.7 billion, as of February 13. The publishing magnate Samuel Newhouse Jr. is second with $7.5 billion.

Other prominent New Yorkers on the list are investor George Soros ($7.2 billion); the chairman of News Corporation, Rupert Murdoch ($6.5 billion); Mayor Bloomberg ($5.1 billion); Ralph Lauren ($3.6 billion), and Donald Trump ($2.6 billion). Paychex founder Thomas Golisano ranked 606 overall with $1.3 billion and investor Christopher Flowers of J.C. Flowers & Company came in at 645 with $1.2 billion. Two New York women are on the list: Leona Helmsley ($2.2 billion) and Wilma Tisch, widow of Laurence Tisch, and family ($1.2 billion).

The daughter of the slain Lebanese prime minister, Rafik Hariri, Hind Hariri, was the youngest billionaire on the list, with $1.4 billion. The 22-year-old is just eight months younger than Prince Albert von Thurn und Taxis of Germany, who is worth $1.9 billion.

The gains enjoyed by the world’s ultra-rich coincide with a period of strong growth in global commodity and stock markets, and the creation of new wealth in emerging economies such as India and China. “2006 really belongs to some of the emerging markets,” an associate editor at Forbes, Luisa Kroll, said.

India alone produced 10 new billionaires, including Tulsi Tanti, whose energy company controls Asia’s largest windfarm. His rise in particular reflects the growing importance of alternative energy markets throughout Asia and Europe. The total wealth of India’s elite now tops $99 billion.

In China there were four new entrants, including 35-year-old Internet developer William Ding ($1.2 billion) and the chairman of the property development and investment company Hopson Development Holdings Limited, Chu Mang Yee ($1.1 billion).

“These are very smart individuals with a tremendous work ethic and incredible drive,” Mr. Duffy said. “They’re very quick decision-makers, they’re responsive to trends, and they’re expert at managing risk.” Mr. Duffy said J.P. Morgan has relationships with about 40% of the people on the Forbes list.

Bill Gates is no. 1 for the 12th straight year, with $50 billion, up $3.5 billion from 2005. The gap widened between him and his closest rival, the legendary investor and Berkshire Hathaway chairman, Warren Buffett, whose fortune dropped by $2 billion to $42 billion. The founder of Ikea, Ingvar Kamprad, rose to fourth place from sixth, after his wealth increased by 21% to $28 billion.

The ranks of the billionaires’ club is growing fast. The 18% rise over the last year is an upward trend dating to 2003, when there were 476 members worldwide. That figure rose by more than 23% in 2004 and by almost 18% in 2005. Ms. Kroll, who helped compile the Forbes list, put it simply: “A billion just isn’t what it used to be.”