NEW YORK — These days, it takes a billion — at least.

For the first time, Forbes magazine's list of the 400 richest Americans consists exclusively of people worth $1 billion or more. As a group, the people who made the rankings released Thursday are worth a record $1.25 trillion, compared to $1.13 trillion last year.

In the billionaire-athon, casino magnate Sheldon Adelson pole-vaulted to No. 3 from 15 in last year's ranking, finishing behind the mainstays at Nos. 1 and 2: Microsoft Corp. founder Bill Gates and Warren Buffett of Berkshire Hathaway Inc.

Once again, medical-devices entrepreneur and real-estate developer James LeVoy Sorenson was the richest Utahn on the list. He tied with H. Ross Perot of Dallas for 57th with an estimated net worth of $4.3 billion. That estimate is up from $3.9 billion last year, but it did not keep Sorenson from dropping one spot in the rankings.

Robert Earl Holding, known for his Sinclair Oil company, Little and Grand America hotels and resorts like Snowbasin, used to be a Utahn but now is classified as a resident of Idaho for the Forbes list. Regardless of his state of residence, Forbes reported that his net worth jumped from $1.5 billion in 2005 to $4.2 billion this year. That boosted his ranking from 207th to 59th, just behind Sorenson.

Jon M. Huntsman, founder of Salt Lake-based chemical company Huntsman Corp. and father of Utah Gov. Jon Huntsman Jr., continued his drop in the Forbes rankings, from 198th last year to 242nd this year. His net worth dropped from an estimated $1.6 billion in 2005 to $1.5 billion now.

Among the top three on the list, Adelson is now estimated to have $20.5 billion, Buffett $46 billion and Gates $53 billion. Gates has held the No. 1 spot for the past 13 years while Buffett has been No. 2 every year since 1994 except 2000, when Larry Ellison of Oracle Corp. held that spot.

Adelson's expanding net worth is related in no small part to his decision to open a casino two years ago on the island of Macau, an emerging gambling haven off the southeastern coast of China. Profits are growing rapidly thanks to the Las Vegas Sands Corp.'s Macau casino. Adelson personally and through family trusts controls 60 percent of the company.

Forbes estimates Adelson earned about $1 million an hour over the past two years. In the second quarter alone, the Sands Macau property saw net revenue jump to $310.4 million, up from $205.1 million a year ago. To tap the demand from gamblers in Asia going forward, the Sands Corp. plans a second property on Macau and a casino in Singapore.

The two Google Inc. founders were also big earners. Sergey Brin and Larry Page gained about $13 million a day over the past two years, according to Forbes. That puts them in 12th and 13th place, up from a tie at 16th place last year.