Greg Smith, who worked in equity derivatives in London, wrote a resignation letter that appeared in the New York Times. He said Goldman Sachs was a "toxic" place to work.

Goldman Sachs did issue a short statement in response.

"We disagree with the views expressed, which we don't think reflect the way we run our business. In our view, we will only be successful if our clients are successful. This fundamental truth lies at the heart of how we conduct ourselves."

In an interview with Reuters, Jim O'Neill said "it's very important for me to emphasize that our role as asset managers is a fiduciary responsibility to our clients. It's a legal obligation so it's pretty clear what our purpose is."