The 18 richest people in America

Net worth: $25.2 billion

Age: 86

Country: US

Industry: Hedge funds

Source of wealth: Self-made; Soros Fund Management

Born in Budapest, George Soros lived through the Nazi occupation of Hungary during WWII before fleeing to the UK and later settling in the US. Touted as "the man who broke the bank of England," he's best known for the Quantum Fund, a hedge fund he launched in 1973 under his Soros Fund Management company. In 1992 he shorted the British pound, a risky move that ended up earning the fund $1 billion in a single day and solidifying Soros' place in the finance world. Quantum Fund also generated annual returns over 30% under Soros' leadership, making it one of the most successful hedge funds of all time.

Today, Soros remains chairman of Soros Fund Management, which manages more than $25 billion in assets, including stakes in prominent companies like Amazon, Facebook, and Netflix. He's also chairman of Open Society, an organization he founded in 1979 that operates as a network of foundations and partners across the globe that promote the values of open society and human rights.

Soros' wealth decreased by $800 million over the last year.

Net worth: $27 billion

Age: 60

Country: US

Industry: Tech

Source of wealth: Self-made; Microsoft

Steve Ballmer dropped out of business school at Stanford in 1980 to join Harvard friend Bill Gates at Microsoft as the company's first business manager, earning a $50,000 salary and a stake in the company. During his tenure, Ballmer held positions as vice president of marketing, vice president of systems software, and executive vice president of sales and support, and was often referred to as "the numbers guy."

He became CEO of the company in 2000 after Gates stepped down, and he remained in charge of the software giant until Satya Nadella replaced him in 2014. While running Microsoft, the company's revenue grew by 294% and profits by 181% — although its market share was surpassed by Google and Apple during the same period. Still, the early stake Ballmer acquired in the company made him immensely wealthy.

After stepping down as CEO, Ballmer fulfilled his dream of owning an NBA franchise, paying $2 billion in a deal to buy the Los Angeles Clippers, now his main venture.

Ballmer's net worth has increased $4.8 billion in the last year.

Net worth: $28 billion

Age: 83

Country: US

Industry: Real estate

Source of wealth: Self-made; Las Vegas Sands

The "King of Las Vegas" first hit the jackpot in 1995 when he was 61 and running Computer Dealers' Exhibition (COMDEX), one of the largest trade shows in Las Vegas. That year, Adelson sold the company to Japan's Softbank for $860 million and used the cash to finance his purchase of the Sands Casino. He quickly demolished it and in its place built the Venetian Casino Resort and the Sands Expo Convention Center. After further expansion, he took his gambling conglomerate, Las Vegas Sands, public in 2004.

Adelson, a former reporter and mortgage broker and the son of Ukrainian-Jewish immigrants, was hit hard during the financial crisis in 2008, reportedly losing $25 billion and needing to bolster his company's balance sheet with $1 billion of his own cash. Though the Sands had a rough 2015 — the stock tumbled 25% during the year — his fortune has recovered from the dark days of 2008. His overall net worth rose by $3.2 billion in the last year. He still runs the Sands and is CEO of China Sands, a subsidiary that opened its fifth casino in Macau last year.

The casino magnate, who owns 13 private jets, is a staunch supporter of the Republican Party, famously donating tens of millions of dollars to past candidates like Newt Gingrich and Mitt Romney. He reportedly donated $25 million to aid Donald Trump's presidential bid.

In late 2015, he purchased Nevada's largest newspaper for $140 million.

Net worth: $32.4 billion each

Age: 77 and 81

Country: US

Industry: Candy

Source of wealth: Inheritance; Mars Inc.

Siblings Jacqueline and John Mars inherited a stake in the iconic candymaker Mars Inc. when their father, Forrest Sr., died in 1999. The notoriously private trio co-own but don't actively manage the maker of M&M's and Milky Way bars, which their grandfather started in 1931 as a confectionary business in his kitchen in Tacoma, Washington.

In 2008, Mars Inc. branched out from chocolate to gum, when it acquired the Wrigley Jr. Co. for $23 billion. Since then, it's delved into pet food, buying Iams and two other brands in 2014 from Procter & Gamble for close to $2.9 billion.

Together the siblings run the Mars Foundation, which gives primarily to educational, environmental, cultural, and health-related causes. In March 2015, John Mars was made an honorary knight by Queen Elizabeth II.

Their combined net worth has risen by $2.6 billion over the last year.

Net worth: $34 billion

Age: 67

Country: US

Industry: Retail

Source of wealth: Inheritance; Walmart

The daughter of late Walmart founder Sam Walton, Alice Walton holds a major piece of the company fortune, making her the richest woman on earth. Though she never took an active role in running the superstore like her brothers, she's become the target of pushback from minimum-wage Walmart employees who view her highfalutin lifestyle as insensitive and ignorant to the plights of many workers.

Instead of spending time at Walmart, Walton has become a patron of the arts. Her immense personal collection includes pieces from Andy Warhol, Norman Rockwell, and Georgia O'Keefe. In 2011, she opened the $50 million Crystal Bridges Museum in Arkansas, where a number of her famous paintings are on display.

In 2015, Walton donated 3.7 million of her Walmart shares to the family's nonprofit and put her Texas ranches — one a working horse ranch, the other a luxurious vacation spot — on the market for a combined $48 million.

Her net worth has risen by $2.3 billion over the last year.

Net worth: $35.1 billion

Age: 68

Country: US

Industry: Retail

Source of wealth: Inheritance; Walmart

James "Jim" Walton's parents, Helen and Sam Walton, purchased a controlling stake in Arkansas' Bank of Bentonville the year before opening the first Walmart store in Rogers, Arkansas, in 1962 — when Jim was just 14. Within five years, the family owned 24 of the retail stores and in 1972 listed Walmart on the New York Stock Exchange. In 1975, after working in Walmart's real-estate department for a few years, Jim joined his parents' bank, later renamed Arvest Bank Group. He's now chairman and CEO of the regional community bank, which has $15 billion in assets. Over the last year, Walton's has increased by $2.7 billion.

The businessman is also director of Walton Enterprises, the holding company for the Walton family assets, and chairman of Community Publishers, an Arkansas-based newspaper firm. After the death of his brother John in 2005, Jim joined the board of Walmart, where he serves as a director today.

While America's richest family remains incredibly private, the Walton Family Foundation, of which Jim is secretary and treasurer, has donated millions to charitable causes. In December 2015, Jim and his siblings donated $407 million worth of Walmart shares to a newly formed trust that funds the Walton's philanthropy, which focuses on educational, cultural, community development, and social causes.

Net worth: $35.4 billion

Age: 72

Country: US

Industry: Retail

Source of wealth: Inheritance; Walmart

Samuel Robson "Rob" Walton is the oldest son of Walmart founder Sam Walton. He started working at the iconic retail behemoth in 1969, holding positions from senior vice president to general counsel to chairman, a role he stepped down from in June 2015 after 23 years on the job. His son-in-law was named as his successor.

Regulatory filings on New Year's Eve revealed that Walton and his brother each gave away 1.5 million Walmart shares to the family charity, Walton Family Holdings Trust, while sister Alice gave away 3.7 million shares, for a total family donation of $407 million. It's an incredible amount, but it's also ultimately a drop in the bucket for the Waltons.

His wealth has increased by $3.3 billion in the past year.

Net worth: $41.6 billion

Age: 43

Country: US

Industry: Technology

Source of wealth: Self-made; Google

Along with cofounder Larry Page, Sergey Brin helped facilitate Google's massive restructuring, which the company announced in 2015. The move put Google under the auspices of a holding company called Alphabet, run by Brin as president and Page as CEO. Google's other ventures, such as Nest and Google X, are separate companies also under the Alphabet umbrella.

The restructuring allowed Brin to focus on exploring inventive new "moonshot" projects and ideas. With top talent and an abundance of resources at its disposal, Alphabet has already made automated homes and self-driving cars a reality.

Brin, who emigrated from Moscow to the US as a child, connected with Page in 1995 at Stanford, where they were each pursuing a PhD. Three years later they founded Google, now one of the most powerful companies on the planet.

Over the past year, Brin's wealth has increased by $4.1 billion.

Net worth: $42.5 billion

Age: 43

Country: US

Industry: Technology

Source of wealth: Self-made; Google

As a Stanford PhD student in 1998, Larry Page teamed up with classmate Sergey Brin to create BackRub, an early search engine. The project eventually morphed into Google — now called Alphabet — one of the largest and farthest-reaching companies in the world, worth more than $581 billion. Over the past year, Page's personal net worth has increased by $4.3 billion.

Page oversaw major changes to Google's business structure in 2015, starting with the creation of Alphabet, the holding company that manages Google and all of its related ventures, including Nest, Calico, and Google X. Previously the chief executive of Google, Page moved up to helm Alphabet, which has its hands in everything from home automation to self-driving cars to prolonging human life.

Page doesn't make a lot of splashy purchases, but the alternative-energy advocate does own an eco-friendly mansion in Palo Alto that uses geothermal energy and rainwater capture. He's also an avid kiteboarder.

Net worth: $45.3 billion

Age: 72

Country: US

Industry: Tech

Source of wealth: Self-made; Oracle

In 1977, Larry Ellison teamed up with two colleagues from an electronics company to start their own programming firm, which landed a contract not long after to build a relational database-management system for the CIA under the project code Oracle. The project grew into what is known today as Oracle Corp., which produced $37 billion in revenue last year. In 2010, Ellison reduced his annual salary from $1 million to $1, but he still takes in more than $60 million in total compensation thanks to generous stock awards. Ellison stepped down as CEO in 2014 after 38 years on the job and took on the role of chief technology officer.

The tech tycoon is also a generous philanthropist through partnerships with wildlife conservation groups and the Lawrence Ellison Foundation, which supports organizations that research aging and global infectious diseases. He's also a member of Bill Gates and Warren Buffett's Giving Pledge, committing to give away at least half of his fortune.

In the last year, Ellison's wealth has increased by $5.2 billion.

Net worth: $47.9 billion

Age: 76

Country: US

Industry: Diversified investments

Source of wealth: Inheritance/self-made; Koch Industries

Along with his brother Charles, David Koch runs Koch Industries as executive vice president. The second-largest private company, $100 billion (in sales) Koch Industries manufactures everything from fertilizer and Dixie Cups to asphalt and biodiesel. David's personal wealth has decreased by $1.2 billion billion in the past year.

Famously conservative, the brothers also maintain immense political influence and routinely spend, along with their vast donor network, hundreds of millions on political campaigns and causes.

David has had two brushes with death. He survived a plane crash in 1991 in which everyone else in first class died, and he also won a battle with prostate cancer. He's become one of the world's most generous givers since, pledging to contribute more than $1.2 billion to cancer research, hospitals, education, and cultural institutions over his lifetime through his David H. Koch Charitable Foundation.

Net worth: $47.9 billion

Age: 81

Country: US

Industry: Diversified investments

Source of wealth: Inheritance/self-made; Koch Industries

Charles Koch is chairman and CEO of multifaceted conglomerate Koch Industries, the second-largest private company in America. His younger brother David is the executive vice president. The company employs 100,000 people and generates $100 billion in sales from its diverse holdings, which make everything from petrochemicals and Dixie Cups to raw clothing materials.

Outspoken in the world of conservative politics, the Koch brothers, who have a combined net worth of $95.8 billion, routinely fund political campaigns, although they took a step back during the 2016 election cycle.

However, in "Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right," it was revealed that Charles Koch's plans to reshape American politics date back 40 years, when he began strategizing and developing a libertarian movement.

Net worth: $58.5 billion

Age: 32

Country: US

Industry: Technology

Source of wealth: Self-made; Facebook

In 2004, Mark Zuckerberg, then a 19-year-old sophomore at Harvard, launched TheFacebook.com, a rudimentary version of the now ubiquitous social network known as Facebook. Zuckerberg dropped out of college to work full-time as Facebook's CEO, and the site quickly exploded in popularity. Today, it attracts more than a billion users daily and is worth nearly $400 billion. At 32, Zuckerberg is by far the youngest of the 50 richest people in the world. His wealth has increased by $11.1 billion in the past year.

In December 2015, Zuckerberg and his wife, Priscilla Chan pledged give away 99% of their wealth in their lifetimes through an organization called the Chan Zuckerberg Initiative, though some critics noted the organization wasn't a nonprofit charity itself and found the announcement misleading.

But this isn't the couple's first foray into philanthropy. They donated $25 million in the fight against Ebola in 2015, and they gave $100 million worth of Facebook shares toward improving a New Jersey public-school system.

Net worth: $73.1 billion

Age: 53

Country: US

Industry: Tech

Source of wealth: Self-made; Amazon.com

Jeff Bezos earned his massive fortune by introducing e-commerce to the world. After spending time in finance on Wall Street, Bezos founded Amazon.com in the garage of his Seattle home in 1994 and operated it exclusively as an online book retailer. The company went public three years later and has since grown to include everything from furniture to food to Amazon's own consumer-electronics products, generating $136 billion in revenue in 2016.

Bezos also has interests outside of Amazon, including investments in his privately owned space company Blue Origin, which successfully launched its first spacecraft in 2015, and The Washington Post, the newspaper he bought in 2013.

Bezos' wealth has increased by $21.9 billion in the last year.

Net worth: $77.2 billion

Age: 86

Country: US

Industry: Diversified investments

Source of wealth: Self-made; Berkshire Hathaway

Berkshire Hathaway CEO Warren Buffett started his prodigious investing career at a young age. As a child he delivered newspapers on his bike, and by 11 the precocious Nebraska native had purchased his first shares in the stock market — Cities Service Preferred at $38 apiece — and sold them for a $5 profit. He was rejected from Harvard Business School, so Buffett went to Columbia Business School instead and learned under iconic value investor Benjamin Graham, who would become a mentor to the budding financier. Buffett worked as a securities analyst in the early-1950s before starting his own investment firm. He bought textile company Berkshire Hathaway in 1969, transforming it into a holding company that would house the many lucrative investments that helped build his massive fortune and earn the nickname "The Oracle of Omaha."

The array of portfolio companies and investments that made him rich may appear random — he's bet on companies including Coca-Cola, American Express, Geico, Fruit of the Loom, Dairy Queen, and General Motors — but they're all cash-generating machines that offer long-term value. In the past year, his net worth has increased by $13.1 billion.

A frugal man with a fondness for junk food, perhaps the most impressive part of Buffett's $60 billion fortune is that it doesn't include the more than $25 billion he's already given away. He's good friends with Microsoft cofounder Bill Gates, whom he collaborated with to create the Giving Pledge, a promise for billionaires to give away at least half of their wealth to charity.

Net worth: $85.2 billion

Age: 61

Country: US

Industry: Tech

Source of wealth: Self-made; Microsoft

At just 20, Bill Gates cofounded Microsoft with his childhood friend Paul Allen. Months before his 31st birthday, the company went public, making Gates a billionaire. He served as CEO of the software titan until 2000 and was its chairman and largest shareholder until 2014. Though he still sits on the company's board, Gates is no longer actively involved in Microsoft.

Gates is not only the richest man in the world — his net worth increased by $10.6 billion in the last year alone — but he's also the most generous. Since 1999, Gates and his wife have helmed the Bill & Melinda Gates Foundation, one of the most powerful charities in the world. The foundation — which controls an endowment of more than $40 billion — aims to lift millions of people out of poverty, with a heavy focus on eliminating HIV, malaria, and other infectious diseases. The couple is also working on a plan to bring mobile banking to the 2 billion adults who don't have a bank account.

He's also cofounder of the Giving Pledge, which he launched in 2010 with good friend and fellow billionaire Warren Buffett as a promise to donate 50% or more of their fortunes. The Giving Pledge now counts Mark Zuckerberg and Elon Musk among its 156 members.