The men share a common goal: to protect the interests of big banks in the vast market for derivatives, one of the most profitable — and controversial — fields in finance. They also share a common secret: The details of their meetings, even their identities, have been strictly confidential.

Drawn from giants like JPMorgan Chase, Goldman Sachs and Morgan Stanley, the bankers form a powerful committee that helps oversee trading in derivatives, instruments which, like insurance, are used to hedge risk.

In theory, this group exists to safeguard the integrity of the multitrillion-dollar market. In practice, it also defends the dominance of the big banks.

The banks in this group, which is affiliated with a new derivatives clearinghouse, have fought to block other banks from entering the market, and they are also trying to thwart efforts to make full information on prices and fees freely available.