The Securities and Exchange Commission is preparing new rules to boost oversight of mutual funds, hedge funds and other firms as part of an effort to gain insight into whether the $50 trillion asset management industry poses risks to the financial system, according to people familiar with the discussions.

The SEC is in the early stages of developing requirements, including that asset managers such as Fidelity Investments and BlackRock give regulators more data about their mutual fund portfolio holdings and conduct stress tests on their funds to determine how they would weather economic shocks such as a sudden change in interest rates.