U.S. lawmakers have asked the SEC and FINRA to provide non-public communications and records of Prometheum's special purpose broker-dealer (SPBD) application and approval process. Lawmakers expressed dissatisfaction with the SEC's response on March 26 regarding the classification of Ethereum (ETH) and Prometheum's intention to custody ETH, and set a deadline of June 5 for a response. Prometheum received FINRA's SPBD approval in May 2023 and launched ETH as a security custody service on May 17. Its CEO Aaron Kaplan supports regulating cryptocurrencies under existing securities laws, which has caused controversy in the crypto industry. The Blockchain Association filed a Freedom of Information Act request in June, questioning the transparency of its approval process.