Congress wrote the Volcker rule into law but regulators have broad discretion to determine how to make that a reality through writing and enforcing the regulations.

Staff at the agencies have begun gathering data and have identified potential changes, according to several people familiar with the effort. Work will accelerate once Jelena McWilliams becomes FDIC chair, among the last of Trump's top financial nominees who should be confirmed by the Senate in the coming months.

"You’re going to see momentum start building and start building quickly," said Tom Quaadman, executive vice president with the U.S. Chamber of Commerce.

Spokesmen for the Fed, FDIC, OCC and CFTC declined to comment. The SEC did not respond to a request for comment.

Presumption, Definitions

One major change being discussed would see the reversal of the "rebuttable presumption" which puts the onus on banks to prove their compliance with the Volcker rule. Now, all positions held for fewer than 60 days are considered banned proprietary trading unless banks convince regulators they serve a permitted purpose such as a client trade.

Banks want the burden of proof to shift to regulators, so that all trades will be allowed unless regulators identify an issue while supervising the banks, five people familiar with the discussions said.

Regulators are also considering narrowing the definitions of such terms as "proprietary trading" and "covered funds," they said. The latter prohibits investments in risky vehicles, such as hedge funds, but it also prevents banks from doing less risky business such as some forms of wealth management.

More clarity about what is allowed and what is not would give banks more flexibility in trading and investment, those people said.

Regulators are also considering further steps to exempt certain overseas funds affected by the rule because of links to banks with U.S. operations. Last July, regulators exempted such foreign funds for a year and are now considering a one year extension or possibly making the exemption permanent, two people briefed on the matter said.