The Forbes’ annual US 400 rich list is out, with a recorded combined wealth of $2.34 trillion. Making The Forbes 400 is harder than ever. Admission to the list starts at a record $1.7 billion, up $150 million from a year ago.

The average net worth of a Forbes 400 member is an astounding $5.8 billion, the highest to date, up from $5.7 billion last year.

Microsoft founder Bill Gates continued to dominate the prestigious list for the 22nd year in a row with a $76billion fortune, retaining his No. 1 spot despite losing $5billion from 2014.

One thing it shows is America’s billionaires are getting young: this year there were 17 under-40s on the list, unsurprisingly most of them were techies. These are the top 10 youngest billionaires that made the list this year.

1. Evan Spiegel

The youngest billionaire is Snapchat’s Spiegel, who at age 25 has a net worth of $2.1bn.

2. Bobby Murphy

At 27 years old, Murphy, the co-founder of Snapchat with Spiegel, is worth $1.8bn.

3. Julio Mario Santo Domingo, III

Santo Domingo inherited his grandfather’s 15 per cent stake in the world’s second largest brewer, SAB Miller (which is expecting a takeover offer from its rival AB INBev). AT 30 years old, he’s worth $23bn.

4. Mark Zuckerberg

At 31, Facebook founder Zuckerberg made it into the top 10 for the first time ever, ranking seventh, with a net-worth of $40.3bn.

5. Dustin Moskovitz

Moskovitz, 31, is one of Facebook’s co-founders. He’s  since left the company and founded his own software firm Asana. Worth $8.4bn.

6. Elizabeth Holmes

Holmes, also 31, is the youngest woman on the list. Worth $4.5bn, she’s developed a new blood-testing technology, and founded her company Theranos to help detect a range of diseases.

7. Scott Duncan

Duncan, 32, inherited his father’, Dan Duncan’s Texas oil pipeline fortune and is now worth $5bn. He was left Enterprise Products Partners in 2010 alongside his three siblings, but is not involved in the business.

8. Nathan Blecharczyk

Aged 32, Blecharczyk is the youngest of the co-founders of Airbnb, which is now valued at more than $25bn, and chief technology officer for the company. He is worth $3.3bn.

9. Brian Chesky

The 34-year-old former body-builder Chesky is the chief executive and co-founder of Airbnb, and is worth $3.3bn. He recently published the seven rejection letters he received when first looking for Airbnb funding.

10. Joe Gebbia

Gebbia, 34, also made his $3.3bn fortune from Airbnb. He is another co-founder and the chief product officer.