Hedge funds are about to become a bit less mysterious.

Many will have to make limited disclosures to the Securities and Exchange Commission and answer to its regulators under rules the agency adopted Wednesday.

The SEC was acting at the behest of Congress and President Obama, who last year demanded greater oversight in legislation responding to the financial crisis.

The new requirements “will fill a key gap in the regulatory landscape,” SEC Chairman Mary Schapiro said.

The funds won’t have to bare their innermost secrets. But they will have to publicly disclose general information about their size and ownership, and who is auditing their books, among other matters.

To spotlight practices that might harm investors, the SEC said, the funds will have to reveal potential conflicts of interest, such as whether they pay anyone to send them clients.

Hedge funds, which often employ exotic strategies that can yield outsize profits, invest money for wealthy individuals and institutions such as endowments and pension plans.

As of early 2009, they managed $1.5 trillion, according to data cited by the Managed Funds Association, an industry group.

Managers or “advisers” of these private funds have been able to avoid registering with the SEC under a rule that exempts advisers with fewer than 15 clients, because each fund counted as a single client, even if it had scores of investors.

Many funds are already making voluntary disclosures to the SEC.

The legislation the SEC was carrying out, known as the Dodd-Frank Act, extends the expanded oversight to private equity funds, too.

The SEC split 3 to 2 on the key vote Wednesday, with two Republican commissioners opposing the measure.

They argued that the SEC went further than it should have by requiring some disclosures from fund managers that, under the law, it could have exempted from the new requirements.

The law exempted managers of venture capital funds, managers of private equity and hedge funds that manage less than $150 million in the United States, and foreign fund advisers with no offices in this country.

The SEC extended some of the requirements to venture capital and private equity funds. For example, they must report whether they or their employees have significant disciplinary histories.

“Every dollar that is spent by a venture capital fund to satisfy the commission’s newly imposed regulatory requirements is a dollar that cannot be invested in the next Google, Apple, or Amazon,” Republican Commissioner Kathleen L. Casey said in a statement.

It remains unclear how much the SEC will be able to do with its new regulatory authority. Agency leaders have said the SEC’s budget has not kept pace with its growing responsibilities.

But many hedge funds that previously reported to the SEC — an estimated 3,200 of the 11,500 now registered with the agency — will in the future become the responsibility of state regulators, the SEC said. Previously, fund managers could register with the SEC if they had at least $25 million under management; that threshold was raised to $100 million.

The SEC cut venture capital funds some slack, saying they could invest up to 20 percent of their money in investments that don’t fit the description of venture capital and still qualify for lighter regulation.

Also beyond the reach of the new regulations are family offices — enterprises created to manage the fortunes of individual families.

To separate them from money managers that serve unrelated clients, the SEC had to define “family.”

The agency settled on all lineal descendants of a common ancestor no more than 10 generations in the past. That includes stepchildren, adopted children, spouses and “spousal equivalents.”