Who is fidelity regulated by?

I understand that Fidelity is a well-known financial services company that operates in various areas, including investments, asset management, and even cryptocurrency. But when it comes to regulation, I'm curious to know who oversees Fidelity's operations to ensure compliance with laws and regulations. Is it a specific government agency, or a combination of multiple regulators? Additionally, does the type of services Fidelity offers, such as its involvement in the cryptocurrency market, impact the regulatory body that oversees it? Clarifying these points would help me better understand the regulatory landscape surrounding Fidelity.