Washington ? Federal regulators responded to the mutual fund scandal with proposals Wednesday that would require ethics codes for fund-managing investment firms and would bolster the independence of fund board chairmen and directors.

At the same time, the Securities and Exchange Commission was widening its fund investigation by looking into several cases in which brokerage firms steered clients toward certain funds in exchange for payments — inadequately disclosed — from those fund companies.

As part of the proposals put out for public comment Wednesday, the agency would require that fund investors get more information about such arrangements, even before they buy funds.

The SEC’s inspection of brokerage houses that sell mutual funds has uncovered widespread payments to the brokerages from the firms that manage funds, in return for favorable treatment of specific funds.