Mr Trump saw his fortunes take a hit by $800 million over the last year, with the real estate tycoon dropping 35 spots on the Forbes list from 121st to the 156th spot this year.
At 42, more than 10 per cent of those on the 2016 list of The Forbes 400 of the wealthiest people in America are immigrants who have achieved great business success in the country. Of these 42 on the list, 14 tycoons have amassed a fortune bigger than Mr Trump's, Forbes said.
Mr Trump's fortune slid to $3.7 billion from the $4.5 billion. It was last year due to "cooling property prices and new information about his holdings".
Forbes said foreign-born members of The Forbes 400 have a combined net worth of nearly $250 billion. Coming from 21 different countries, the immigrants are a crucial fabric of the American economic growth story.
"From the proverbial garage in Silicon Valley to the boardroom of Wall Street, the immigrant American dreamers remain a key cog in the American entrepreneurialism machine," Forbes said.
Among the notable foreign-born members of America's rich list are Google co-founder and Alphabet president Sergey Brin, who leads the pack as the wealthiest immigrant billionaire, with a $37.5 billion fortune.
Mr Brin is one of four The Forbes 400 members who were born in the former Soviet Union, and went on to pursue a PhD at Stanford University, where he met Larry Page and dropped out to start Google.
Mr Brin, along with investor and philanthropist George Soros, Tesla CEO Elon Musk, media baron Rupert Murdoch, WhatsApp co-founder Jan Koum and eBay founding president Jeffrey Skoll, is among the 14 immigrants on the Forbes list now richer than Mr Trump.
A University of Pennsylvania alum who's now worth $11.6 billion, Mr Musk was born in South Africa to an engineer father, and reportedly started programming video games as a preteen.
An advocate for refugees, Mr Soros lived through the Nazi occupation of Hungary during the Second World War and is now the richest hedge fund manager in the world with a $24.9 billion net worth, Forbes said.
European immigrants took up 15 of the slots on the Forbes list of America's richest. As a single nation, Israel leads the lot as the top exporter of Forbes 400 talent with six members on the list, while India has five and Hungary and Taiwan are tied for third with four.
Symphony Technology founder Romesh Wadhwani, co-founder of outsourcing firm Syntel Bharat and Neerja Desai, Airline veteran Rakesh Gangwal, entrepreneur John Kapoor and Silicon Valley angel investor Kavitark Ram Shriram are the Indian-origin persons on the list.