www.fintechandpayments.com/2021/01/sec-issues-guidance-for-broker-dealer-custody-of-digital-assets/#page=1
www.findknowdo.com/news/12/23/2020/sec-requests-comment-broker-dealer-custody-digital-asset-securities?utm
www.vedderprice.com/investment-services-regulatory-update-april-2021