Companies overseeing a combined $53 trillion in assets, led by fund giants BlackRock Inc. and Vanguard Group Inc., can contribute to asset price increases and magnify volatility during sudden shocks, a report by the Treasury said Monday. Gaps in data, particularly on investments managed for institutions, limited the study’s ability to identify additional risk.

“A certain combination of fund- and firm-level activities within a large, complex firm, or engagement by a significant number of asset managers in riskier activities, could pose, amplify or transmit a threat to the financial system,” the Treasury’s Office of Financial Research said in the report.

The study was conducted by the OFR to help the Financial Stability Oversight Council analyze whether asset managers should be considered systemically important and subject to Federal Reserve supervision.

“The council will review the study closely as it considers potential next steps relating to asset management activities and firms,” Treasury spokeswoman Suzanne Elio said in an e-mail.

The council is authorized under the Dodd-Frank financial regulatory law to identify companies that could pose a threat to stability. The Fed can impose on such firms tighter capital, leverage and liquidity rules and demand measures including stress-testing and wind-down plans.

The council, or FSOC, is led by Treasury Secretary Jacob J. Lew and includes Fed Chairman Ben S. Bernanke.

Systemically Important

FSOC has designated three non-bank financial companies — American International Group Inc., General Electric Co.’s finance unit and Prudential Financial Inc. — as systemically important.

Exchange-traded funds “may transmit or amplify financial shocks originating elsewhere” by pooling assets into illiquid investments, like emerging market stocks or high-yield debt, the OFR said. ETFs are baskets of securities, typically tracking an index, that trade on an exchange like stocks.

“Herding into more illiquid investments may have a greater potential to create adverse market impacts if financial shocks trigger a reversal of the herding behavior,” the OFR said.

Mike McNamee, spokesman for the Investment Company Institute in Washington, John Woerth, of Valley Forge, Pennsylvania-based Vanguard, and Brian Beades, at New York’s BlackRock, declined immediate comment because their organizations hadn’t fully reviewed the report.