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."

"I believe I have worked here long enough to understand the trajectory of its culture, its people and its identity. And I can honestly say that the environment now is as toxic and destructive as I have ever seen it."