Jewish billionaire businessman Carl Icahn is encouraging his eldest son to hone his money-making skills — with the help of a $3bn grant.

The American hedge fund manager, 76, allocated the cash to his son, Brett, to invest in listed companies worth up to $10bn.

While Mr Icahn senior will retain overall control of the portfolio of Icahn Enterprises, the family’s $24bn holding company, Brett will have day-to-day discretion over how to invest his grant.

Mr Icahn junior, 33, has worked as an analyst at Icahn Enterprises since he graduated from Princeton University 10 years ago.

Mr Icahn senior, who also attended Princeton, went on to New York University School of Medicine before dropping out to become a renowned corporate financier.

“One of the greatest things I did for the human race was not to become a doctor,” Mr Icahn senior has said.

Mr Icahn senior is noted for his active involvement in charities.

In 2004, he made a $25m donation to the Mount Sinai Medical Centre in New York, and in 2010 pledged to donate at least half of his earnings to worldwide charities.