12 CFR Part 12 establishes rules, policies, and procedures relevant to recordkeeping requirements for specific securities transactions effected national banks for customers. With a few exceptions, this applies to any security transaction effected for a customer by a national bank.
Link to CFR Part: https://www.ecfr.gov/cgi-bin/text-idx?SID=2240159c84d2d3b48422a5185ff69dea&mc=true&node=pt12.1.12&rgn=div512