Prometheum Capital has become the first broker-dealer to be approved by the Financial Industry Regulatory Authority (FINRA) with custody rights for digital asset securities. The company's platform, which will go live in Q3, will only allow trading of assets that meet the definition of securities as determined by the company's compliance operation. However, questions remain about what assets trading platforms will be able to trade, as the vast majority of crypto assets are unregistered securities, and so are in violation of securities laws. Prometheum's broker-dealer will maintain custody of customer assets, potentially making it the only regulated crypto custody provider.