BBX, which was launched in 2020 to simplify bond investing, is the world's first fractional bond exchange. The deal will enable Citi's clients who meet a certain criteria, to become participants on the exchange and trade bonds, with the investment bank providing settlement and custodial services. "The proprietary digital custody technology is scalable and will allow us to provide settlement and custody services for clients investing in assets issued on permissioned blockchain networks and digital financial management information systems (FMIs)," said Nadine Teychenne, head of digital assets for Citi Securities Services.