On a blustery night in New York recently, almost 500 assorted employees of Wall Street banks and other US financial groups gathered in a smart hotel. To the casual eye, it looked like a typical awards ceremony or corporate event.

The chino-wearing participants sipped apple martinis, while placards displayed the logos of banks such as Goldman Sachs, JPMorgan, Merrill Lynch, Pittsburgh-based PNC and BlueMountain Capital, one of the fastest- growing and largest US credit funds.