(Bloomberg News) U.S. Securities and Exchange Commission members may vote as soon as next month on a proposal to overhaul regulation of the $2.5 trillion money-market fund industry, according to a person with knowledge of the matter.

The SEC's five commissioners are expected to receive a formal proposal next week prepared by staff in the agency's investment management division, according to the person, who isn't authorized to speak publicly about internal planning. Commissioners typically spend at least a month reviewing staff proposals before voting on them, the person said.

"It's premature to talk about next steps before the Commissioners have had an opportunity to review an actual proposal and give it some thought," John Nester, an SEC spokesman, said yesterday in an e-mail statement.

SEC Chairman Mary Schapiro has faced opposition from the fund industry and within the commission as she seeks changes to restore investor confidence shaken by the 2008 credit crisis. Schapiro told the Senate Banking Committee last week that she envisions a system in which money funds either allow net asset values to float or hold capital and restrict withdrawals.

Treasury Secretary Timothy F. Geithner and Federal Reserve Chairman Ben S. Bernanke have echoed Schapiro's view that the current system leaves money market funds, once seen as among the safest of investments, vulnerable to runs that could freeze the broader credit markets.

U.S. money funds held a combined $2.5 trillion in assets on June 20, according to the Investment Company Institute, a Washington-based trade group. The largest funds include JPMorgan Prime Money Market Fund, Fidelity Cash Reserves and Vanguard Prime Money Market Fund.

Industry Opposition

The U.S. Chamber of Commerce has led the fight against the changes sought by Schapiro, blanketing a Washington subway station adjoining SEC headquarters with ads questioning the need for a rules overhaul and releasing a study this week suggesting that even proposing changes could roil markets.

Republican SEC Commissioners Troy Parades and Daniel Gallagher have joined Democrat Luis Aguilar in questioning the need for some of the provisions Schapiro has described, such as the floating net asset value.

Schapiro must secure the votes of at least three of the five commissioners to release a proposal for public comment.

Concern over money funds grew after the September 2008 collapse of the $62.5 billion Reserve Primary Fund, which fueled a broader run at the height of the worst financial crisis since the Great Depression. The run calmed after the Treasury Department temporarily guaranteed money-fund shareholders against losses and the Fed began buying fund assets at face value to help them meet redemptions.