Global regulators moved to rein in risk at the world's biggestmoney managers led by BlackRock Inc., calling for new curbs ontrading activities to protect against the potential that losses atinvestment funds could threaten the broader financial system.

The Financial Stability Board (FSB), whose members include theU.S. Federal Reserve and the Bank of England, said on Wednesdaythat exchange-traded funds (ETFs), mutual funds, and other fundsdeserve extra oversight to ensure they can sell assets to meetinvestors' demands to pull out their money during volatile markets.While there is scant history of funds spreading risk throughout thesystem, the growth of the $76 trillion industry and funds' moveinto more complex assets have drawn regulators' attention, the FSBsaid.

The FSB said it may still move to designate certainasset-management companies as systemically important and in need ofstricter supervision. For now, authorities are planning to requirefunds to provide greater disclosure to clients about risks and tostrengthen internal standards for managing investments in stressedmarkets. Regulators also plan to beef up rules for overseeingfunds' leverage and use of derivatives and to reviewasset-managers' lending of securities to other parts of themarket.