Steven Good was discovered parked in a forest preserve near Chicago on Monday morning, the Kane County Sheriff's Department said.
There was no note found in his red Jaguar indicating a motive and it was unclear whether his death was related to his work.
Mr Good's death came hours before that of German billionaire Adolf Merckle, who threw himself under a train after he was brought to the brink of ruin by the financial crisis.
A French investment manager, Thierry de la Villehuchet, who lost more than US$1 billion (S$1.47 billion) in the alleged pyramid scheme of Wall Street titan Bernard Madoff killed himself last month.
Mr Good was the chairman and chief executive of Chicago-based Sheldon Good & Company Auctions International.
The firm says it has sold over 40,000 properties at an aggregate total of over US$9.5 billion since it was founded by Mr Good's father in 1965.
Mr Good, 52, was the driving force behind the firm's expansion and was involved in four billion dollars in sales, according to a company biography.
Company president Alan Kravets hailed Mr Good as 'one of his industry's most brilliant minds and most successful entrepreneurs' and offered his condolences to Good's wife, children and father.
'It is testimony to Steve's leadership that Sheldon Good & Company remains well positioned for the future,' Mr Kravets said in a statement. -- AFP