Final answer:
The Trust Indenture Act of 1939 is the federal law that requires the appointment of an independent corporate trust for bondholders, distinguishing it from other legislation related to securities and banking regulation.
Step-by-step explanation:
The federal law that protects the interests of bondholders and requires the appointment of an independent corporate trust to act as an intermediary between the borrower and the lender is the Trust Indenture Act of 1939. This act ensures that the bond issuers adhere to a formal agreement with the trust that represents the bondholders' interests, providing more security for their investments. The Securities Exchange Act and the Securities Act are related to securities regulation and disclosure of information, while the Federal Reserve Act established the modern central banking system but does not specifically deal with the relationship between bond issuers and bondholders.