In the interim, the bankers had sold dollars to speculators, at sharply higher exchange rates.
A banker, on the other hand, lends out its own money and then either sells the loan on the secondary market or keeps it in its own portfolio.
If interest rates drop and the portfolio has a higher average interest rate, the banker can sell the loans at a larger profit based on the difference in the current market rate.
I asked why such money-changing was needed and was told: "The banker doesn't sell sweaters and I don't sell money."
In the same way that bankers in the city sell useless products, all backed up with sale skills that would make a used car salesman weep with envy.
Mr. Calero's bankers had been especially accommodating and had sold him unsigned checks.
"It used to be that a banker would sell his daughter to get into China," said a foreigner in Beijing.
If bankers simply sell property at the first sign that anybody is willing to buy it, they will do themselves and the property market a disservice.
The banker could then sell the notes for dollars to private investors, who would turn them in for full face value in pesos.
Jim Schlosser, executive director of the North Dakota Bankers Association, said last week: "Our bankers do not sell information.