The report describes a $40 trillion investment-management industry that includes retirement programs, private equity firms and $2.4 trillion in specialty funds that banks use to manage their assets. It warns that futures dealers who handle swaps, commodities and foreign-exchange agreements could have a systemic impact if a "large default" set off a chain reaction within the industry.

Regulators may want to collect data from broker-dealers on their market share, concentration and counterparty exposures, along with any hedging and off-balance-sheet activity, the study said.

"Firms that are concentrated in particular assets or sources of funding and revenues are susceptible to shocks from those assets or sources," the study said in its list of possible data requests. "Large exposure to particular counterparties increases the likelihood that shocks to those counterparties will affect a firm."

Derivatives Exposure

Mortgage companies might be asked in a survey for their potential, current and future exposure on derivatives. Likewise, real estate investment trusts, or REITS, could be asked about their derivatives exposure and the identity and exposure of their counterparties, the study said.

Financial companies don't have any incentive to disclose more information than they do now, said Thomas Cooley, an economics professor at New York University's Stern School of Business.

"Opacity has been the friend of Wall Street firms," said Cooley, who studies issues related to financial stability. "At least they see it that way. They probably make more money when people don't know exactly what they are doing."

Data can be used as a "starting point" that can be supplemented by a more detailed analysis of each financial firm, he said.

The data collection and analysis may be more important than the designations, said John Douglas, a partner in the financial institutions group of Davis Polk & Wardwell LLP in Washington.

'Gentle' Process

"A gentle information-gathering process from large, interconnected institutions is more useful and valuable than trying to make some artificial determination at this point as to which ones are systemically important," Douglas said. "Knowledge and information will be extremely valuable, not some list."