How the Richest 400 Americans Made Their Money [INFOGRAPH]

From hedge funds to Beanie Babies, and from big oil to Panda Express, the Forbes 400 richest billionaires in America represent a wide range of industries in America. But which industries are home to the most billionaires?

NerdWallet’s Forbes 400 infographic breaks down the numbers behind the Forbes 400 Richest Americans to find out which industries are the most prominently represented among the superrich. Using the Forbes 400: The Richest People in America list’s data, we found that out of the 400 households listed, just over half (205 households) made their fortune in either finance, retail, tech, and oil & energy. These are also the top 4 represented industries on the list.

We also found:

* The net worth of this year’s 400 richest Americans is $1.7 trillion dollars – a 13% growth in their collective wealth over the 2011 billionaires list.

* The average net worth of these billionaires is $4.2 billion.

* The average age of a top billionaire is 65 and three-quarters years old.

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