 "Two Indian-Americans among richest entrepreneurs under 40")
Vivek Ramaswamy, 30, a former hedge fund manager, has been ranked 33rd on the list with a net worth of $500 million. Forbes said his source of wealth is investments.
On the 40th spot is 29-year old Apoorva Mehta, the founder and CEO of Instacart, the web-based grocery delivery service.
Mehta's net worth is $400 million.
Zuckerberg leads the pack with a net worth of $47.1 billion, more than four times as much as the second person in the ranks, his cofounder and college friend Dustin Moskovitz.
At number three is Jan Koum, who came to America at age 16.
He started WhatsApp, now the world's biggest mobile messaging service with 800 million users in 2009 and sold it to Facebook for about $22 billion in cash and stock in 2014.
Forbes said California techies dominate the first ever list of the nation's 40 most successful young entrepreneurs under the age of 40, "reaffirming the American Dream and proving yet again that there is no better way right now to get rich fast than to go west and convince venture investors to back yourmost ambitious ideas."
Elizabeth Holmes is the only woman to make the 'America's Richest Entrepreneurs Under 40'.
Holmes quit Stanford at age 19 to start blood testing company Theranos.
However recently in a setback, the FDA told Holmes that her company was using an unapproved blood collection device.
All of the young entrepreneurs in the list have net worths of $400 million or more and 34 made their money in the tech sector.
Twenty-one are billionaires and many either created or work for some of the hottest tech companies, including Uber, AirBnB, Fitbit, GitHub, Instacart and Pinterest.
The list's youngest member is Palmer Luckey, who was just 21 years old when he sold his virtual reality equipment company, Oculus, to Facebook for $2.3 billion in July 2014.
Luckey's net worth is $700 million and is one of half a dozen in the ranks who are still in their 20s, Forbes said.