The Securities and Exchange Commission proposed that mutual funds disclose their portfolio holdings four times a year, instead of twice a year.

Fund advocates and financial data providers have long lobbied for more frequent disclosure of fund holdings, which can be out of date when potential investors look at them.

For example, funds delay publishing their portfolio holdings by two months, so a semiannual report that investors get at the end of February would show holdings as of Dec. 31. An investor buying in August, just before the next report is released, could be looking at 8-month-old data.

Under the proposed rule, funds' complete holdings would be available through Edgar, the SEC's online service. Investors can also request copies through the mail. The rule would ''make it easier for those who want to do holdings-based research,'' says Don Phillips, president of Morningstar, the fund-trackers.

The proposed rules make the disclosure a bit easier on funds, too. Funds could give investors a summary portfolio instead of the complete portfolio in semiannual reports.

The summary includes the fund's 50 largest holdings, as well as any holdings that are 1% or more of the fund's portfolio. And money market funds won't have to send investors their holdings at all.

But all funds would have to file complete holdings with the SEC once a quarter and mail them to investors free of charge on request.

Not everyone is convinced investors want more disclosure.

''Based on the research we did, it's a vocal minority who want it,'' says Barry Barbash, a securities lawyer and former head of the SEC's Division of Investment Management, which oversees funds. ''The typical investor doesn't care nearly as much as some advocates suggest.''

Others say more disclosure will let others duplicate fund strategies.

''It's sort of cheating the system, taking advantage of proprietary research,'' says Paul Stevens, partner at Dechert, an international law firm.

Despite the fund industry's reservations about the rule, 95% of all funds voluntarily provide Morningstar with portfolio data quarterly, Phillips says.

Funds would also have to detail, in dollars and cents, how much their expenses cost shareholders. One example would show how much a shareholder paid on a $10,000 investment for the quarter, using the fund's actual returns and expenses.

The other would show how much a shareholder would pay on a $10,000 investment and a theoretical 5% return. This example would let investors compare costs between funds.

The SEC's proposed rule will be available for public comment for 30 days.