It could well be the most destructive resignation letter of all time. Goldman Sachs executive Greg Smith, who managed more than $1 trillion during his time with the fabled Wall Street firm, has published a scathing attack on his employer in the New York Times, slamming a culture where clients were called "muppets" and profits were all that matter.

Smith, who was until today the head of the company's United States equity derivatives business in Europe, the Middle East and Africa, said in his article that "the interests of the client continue to be sidelined in the way the firm operates and thinks about making money."