Mayor Bloomberg is seeking to broaden the investments he makes for personal and philanthropic purposes, and a panel ruled today he can do so if the money management is cloaked in a layer of anonymity.

Mr. Bloomberg sought the Conflicts of Interest Board ruling as a follow-up to its initial recommendation in 2002, the first year he took office. He left his financial information company, Bloomberg LP, to run for mayor, but retained a majority stake in the business.

In 2002, the board ruled Mr. Bloomberg could keep that stake in the company but had to divest himself of at least $45 million in publicly traded stock, and his interest in a hedge fund. The ruling held that his ownership of stocks in companies that do business with the city violated the City Charter.

The board said Mr. Bloomberg could invest his holdings in large, diversified mutual funds “managed by money managers with whom he has no relationships.”

In a new ruling issued today, the board said Mr. Bloomberg had asked its advice because he is seeking to diversify his personal assets and those of his philanthropic foundation. The mayor’s wealth is estimated by Forbes magazine at $11.5 billion.

Despite ongoing speculation that he will enter next year’s presidential race as a self-financed independent, Mr. Bloomberg insists he will complete his second term through 2009 and then focus full time on his charitable giving. He has recently purchased two buildings near his home in Manhattan that he is turning into the foundation’s headquarters, and he has set up the organization with an initial $500 million, tax forms show.

In his request for the board’s ruling, Mr. Bloomberg proposed to put his money in a greater variety of investments than the mutual funds and exchange-traded funds originally approved by the board in 2002.

Those could include commodities, currencies, real estate, hedge funds, private equity funds, and traditional investments like fixed income and equity securities.

A Bloomberg spokesman, Stu Loeser, said that the mayor made the request because “as director of the foundation, he has a responsibility to maximize the amount of money it has to give away to charity.”

To the board, Mr. Bloomberg proposed that one or more investment firms would oversee his personal assets and those of the foundation. The firms would choose a number of third-party asset managers who would actually manage the investments.

He would consult with the investment firms about general allocations of funds or hiring and firing of the managers, but would have no specific information about the holdings.

The board ruled that this arrangement was acceptable and did not create a conflict of interest, but was specific that Mr. Bloomberg could not know the identities of the managers or the investments they make. He could choose to hire or discharge managers, but could only evaluate them by performance and not their identities.

His discussions with the investment firms should not be about specific investments but about the performance of money managers as well as broad sectors and categories of investments.

The board noted that simply because of Mr. Bloomberg’s “celebrity,” it is possible that his specific investments could inadvertently become public or otherwise disclosed to him. Therefore, the ruling said, his investment firms and managers must take “diligent steps to keep confidential” the investments that are made on his behalf.

The board said he must also disclose the investment firms to the board, once he has chosen them, and must recuse himself in his official capacity from all city matters involving those firms.

Mr. Loeser said Mr. Bloomberg would comply with the board’s recommendations.