The US regulators are studying BlackRock and Fidelity Investments to determine if asset managers pose potential risk to the financial system, Bloomberg News has reported.

The review follows a study by the US Treasury Department in September that found some activities of asset managers to be risky to the broader marketplace.

The decision by the Financial Stability Oversight Council to review the two firms does not mean it will necessarily designate them as systemically important, the publication said.

Asset managers are one among the non-bank financial companies that the Financial Stability Oversight Council (FSOC) is empowered by law to evaluate and determine whether their failure could threaten the entire system.

Fidelity Investments spokesman Vincent Loporchio said they continue to believe that the asset-management industry and mutual funds in particular, do not present the types of risk that the FSOC was designed to address.

BlackRock spokesman Brian Beades said the company does not comment on rumour or speculation.