In 1950, Bloomingdale was persuaded to invest in the personal credit business, a new concept gaining ground among the wealthy of the world.
Carrying cash could be a burden. Why not sign for the charge, as one might at a hotel dining room or a private club?
He founded Dine and Sign, then cobbled together 22 Manhattan restaurants that agreed to accept payment in plastic.
His firm soon merged with another credit card startup, Diners Club, and Bloomingdale spent the next 20 years building the business, eventually introducing his card in 130 countries. He became known as the father of the credit card when he predicted that cash would some day become obsolete.
But the Diners Club name positioned it as a niche card, for use in restaurants. The firm had difficulty keeping up with American Express and other cards used for more broad purchases.
In 1969, Bloomingdale stepped aside as chairman of Diners Club.
At that point he had more money than he could ever spend. And retirement gave him ample time for new pursuits, including a certain honey-blond teenager.