Management and its associates often profit the most when federally chartered savings and loan associations convert from mutual to stock forms of ownership, a study by the General Accounting Office said yesterday.

The study, conducted at the request of Senate Banking Committee chairman William Proxmire (D-Wis.), looked at eight of the 25 conversions which have been carried out under an experimental plan adopted by Congress and the Federal Home Loan Bank Board, which regulates S&Ls.

The GAO report also said the bank board "needs to increase its monitoring of associations to determine whether they are complying with conversion regulations."

Proxmire, in a statement, said the report shows that insiders at S&Ls, by a series of techniques, purchase more stock than they deserve to gain control of the S&L which converts its form of ownership. "The prize is the millions of dollars in equity capital in mutual institutions built up over many years by the saving public," Proxmire charged.

The GAO, the Congressional watch-dog agency, said its study was a limited one but recommended that Congress continue to limit the number of S&Ls that can convert.

In late 1974 Congress said that as an experiment the Federal Home Loan Bank Board should devise regulations for conversion and allow no more than 49 federally chartered S&Ls to convert to stock ownership.

That limit expired on June 30, 1976, although to date the bank board has acted on no more than 25 applications out of 73 than have been received.

Federally chartered savings and loan associations - except for recent conversions - technically are owned by their depositors. To continue to expand and conform to net worth regulations of the bank board, many federal savings and loan associations want to issue stock. Many state-chartered S&Ls, which also do not have federal deposit insurance, are stock institutions.

"The most important issue," the GAO report said, "is the desirability of placing these mutual business enterprises into private hands without enriching insiders at the expenses of savers who contributed to the association sequity."

Under bank board rules, savers have first crack at the stock in approximate proportion to their share of savings in the institutions as of a certain date.

But in many of the eight conversions the GAO reviewed, "members of management and their associates significantly increased their holdings through stock transfers soon after conversion. They also increased their savings accounts close to the expected record date of conversion, thereby obtaining rights to purchase stock to which they were not otherwise entitled."

The GAO report charges that in two of the conversions "there was activity which suggests that prearrangements could have been made which were not discovered by the board."

The report cites one instance where management obtained large quantities of stock on the issuance date from four individuals who transferred much of the stock they acquired to the management officials. "The acquisition on the stock issuance date increased management's holdings from 5 per cent to 31 per cent," the report said.

In another conversion," a business associate of management and an estate for which a director was a co-executor transferred 22,901 shares to a member of management within three months of the stock issuance date."

The board, in a November 1976 ruling, prohibited any offers to purchase stock or transfer subscription rights during the conversion process. Also, individuals must certify they are buying stock for themselves and have "no agreement with a member of managemet to transfer such shares to them."

Proxmire said he plans to hold hearings on conversion soon.

The bank board, in a statement, said the GAO study was "fair and objective" and that "we also have generally recognized the same problem areas as has GAO and have taken appropriate steps to strenghten our conversion procedures."