This also is about unregistered securities and not interest bearing accounts although that too is an issue because they're not banks.
edit: They're Money Services Businesses and that's it. They might have some state-level lending licenses but I'm fuzzy on that.
> The Federal Deposit Insurance Corporation (FDIC) is a United States government corporation supplying deposit insurance to depositors in American commercial banks and savings banks.
https://www.sifma.org/resources/general/firms-guide-to-the-c.... :
> Any broker-dealer that is a member of a national securities exchange or Financial Industry Regulatory Authority (FINRA) and handles orders must report to CAT. Eligible securities include NMS stocks, listed options, and over-the-counter (OTC) equity securities.
Interledger Protocol works with any type of ledger, has a defined messaging spec, and has multi-hop audit trails: https://westurner.github.io/hnlog/#comment-36503888