Investor Warren Buffett, the head of Berkshire Hathaway Inc., posted another distant second place finish with $58.5 billion, but increased his net worth from $46 billion. Oracle Corp. co-founder Larry Ellison stayed third with $41 billion and was the only member of the top 10 whose net worth was unchanged from a year ago.
Brothers Charles and David Koch, co-owners of Koch Industries Inc., stay tied for fourth with $36 billion each, up from $31 billion in 2012.
Wal-Mart heirs Christy Walton, Jim Walton, Alice Walton and S. Robson Walton took the next four spots, with holdings ranging from $33.3 billion to $35.4 billion, all increasing from year-ago levels. New York City Mayor Michael Bloomberg, the founder of the eponymous financial information company, rounds out the top 10 with $31 billion, up from $25 billion.
According to Forbes, 273 members of the list are self-made billionaires, while 71 inherited their wealth and another 56 inherited at least some of it but are still growing it.
Facebook CEO Mark Zuckerberg returned to the list's top 20 after dropping out the year before. His net worth of $19 billion earned him the No. 20 spot.
Facebook co-founder Dustin Moskovitz also made the list, at No. 85,with a net worth of $5.2 billion. At age 29 and just a few days younger the Zuckerberg, Moskovitz ranks as the youngest member of the list.
On the flip side, the oldest person on the list is 98-year-old David Rockefeller Sr. at No. 193 with a net worth of $2.8 billion.
A total of 20 new people joined the rankings, including Richard Yuengling Jr. of Pennsylvania beer maker D.G. Yuengling & Son, who ranked at No. 371 with $1.4 billion.
Twenty-eight people dropped off the list, including six who died. Those now falling short of the cut include energy tycoon T. Boone Pickens at $950 million, Graham Weston of Rackspace Hosting Inc. at $920 million and Washington Redskins owner Dan Snyder at $1.2 billion.
A total of 48 women made the list including Hyatt Hotels heir Jennifer Pritzker at No. 327. Formerly known as James Pritzker, she's the list's first transgendered member.
According to Forbes, the 400 people on the annual list posted a combined net worth of $2 trillion, up from $1.7 trillion a year ago. That marks their highest combined value ever.
Meanwhile, the average net worth of the list's members rose to $5 billion, also the highest ever, up from $4.2 billion in 2012. Net worth grew for 314 members and fell for 30, Forbes said.
The increases aren't surprising, given that net worth for America's wealthiest people has risen in the years since the financial crisis, widening the gap between the exceptionally well-to-do and the rest of the country.
According to a study of Internal Revenue Service figures released last week, the top 1 percent of U.S. earners collected 19.3 percent of household income in 2012, their largest share in IRS figures going back a century.
U.S. income inequality has been growing for almost three decades. But until last year, the top 1 percent's share of pre-tax income had not yet surpassed the 18.7 percent it reached in 1927, according to the analysis done by economists at the University of California, Berkeley, the Paris School of Economics and Oxford University.
Some economists have speculated that the incomes of the wealthy might have surged in the past year, because they cashed in stock holdings to avoid higher capital gains taxes that kicked in in January.
___
The Forbes 400: http://www.forbes.com/forbes400
