Updated August 7, 2026. Quick answer: you have been told the transfer agent needs a medallion signature guarantee before it will move the shares, and every bank you have called says it will not stamp for a non-customer. 🔴 That refusal is the real problem, and the federal rule that governs this does not fix it — but it does give you one thing to ask for that most people never do.
Who is allowed to stamp, as a matter of law
The SEC rule defines an “eligible guarantor institution” as a class, and it is broader than “my bank”: it includes banks, brokers and dealers, credit unions, national securities exchanges, registered securities associations, clearing agencies, and savings associations.
⚠️ The practical consequence is the one worth acting on: if you or the decedent held an account at any institution in those categories — including a brokerage where the securities themselves may sit — that is a candidate, and a brokerage is very often an easier route than a retail bank branch.
🔴 The transfer agent must have written standards — ask for them
This is the part nobody tells heirs. The rule requires that every registered transfer agent shall establish:
(1) Written standards for the acceptance of guarantees of securities transfers from eligible guarantor institutions; and (2) Procedures… to ensure that those standards are used in determining whether to accept or reject guarantees…
And those standards “shall not establish terms and conditions… that, as written or applied, treat different classes of eligible guarantor institutions inequitably.” A transfer agent also “shall not… engage in any activity in connection with a guarantee, including the acceptance or rejection of such guarantee, that results in the inequitable treatment of any eligible guarantor institution or a class of institutions.”
So the transfer agent’s requirements are not improvisation, and they are not secret. Asking for the written standards turns “we need a medallion” into a specific, checkable list of who it will accept — which is what you need before you spend another week calling branches.
⚠️ What the rule does NOT do, stated plainly
It constrains the transfer agent. It does not constrain the guarantor. Nothing in it requires any bank, broker or credit union to give you a guarantee, and no institution is obliged to stamp for someone who is not its customer. The rule makes the receiving end predictable; it does not create a right to be stamped.
🔴 Anyone telling you otherwise is overselling it. The realistic route is to find an eligible institution with a reason to help you — an existing relationship, or the brokerage that already holds the assets — rather than to argue the rule at a branch that has no obligation under it.
What actually tends to work
Start with the institution that already holds the securities, then any institution where you or the estate holds an account, then the decedent’s own bank — where the estate relationship itself can be the qualifying one. Bring the authority you have: letters testamentary where probate is open, or a state affidavit where the estate is small enough (small estate limits by state).
Where the assets are savings bonds rather than shares, the route is different entirely: inherited savings bonds has its own procedure.
Sources
Quoted from 17 CFR § 240.17Ad-15 (Signature guarantees), via eCFR, retrieved 7 August 2026: ecfr.gov. ⚠️ sec.gov’s own investor pages returned 403 to this machine, so the regulation text was read from eCFR rather than an SEC summary — which is the stronger source in any case. Medallion programme rules are administered privately and their limits are not stated here, because they are not published in the regulation.