Who Does Signature Guarantees: Banks, Brokers, Medallion Stamps

Signature guarantees for securities transfers are provided by banks, credit unions, savings associations, and broker-dealers that belong to one of three recognized medallion programs. Most will only stamp documents for existing customers, so the practical answer to who does signature guarantees usually starts with the institutions where you already hold an account. Not every branch is set up for it, and the officer who can actually apply the stamp may only work certain days, so a phone call before you drive over is worth the two minutes.

The Institutions Allowed to Issue a Medallion Stamp

Federal rules recognize five categories of “eligible guarantor institutions”: banks, savings associations, credit unions, broker-dealers, and national securities exchanges or clearing agencies.¹ For an ordinary consumer, that means a commercial bank, a credit union, or a brokerage firm.

Being eligible isn’t enough on its own. The institution also has to participate in one of three medallion programs:²

Securities Transfer Agents Medallion Program (STAMP), the largest, with more than 7,000 participating institutions in the U.S. and Canada.
Stock Exchanges Medallion Program (SEMP), covering regional stock exchange member firms along with clearing and trust companies.
New York Stock Exchange Medallion Signature Program (MSP), covering NYSE member firms.

Each participant carries a surety bond that backs every stamp it issues.³ If a guaranteed signature later turns out to be forged and the institution doesn’t pay the resulting claim within ten business days, the transfer agent can collect directly from the bond. That real financial exposure is why these institutions are picky.

Why “Existing Customer” Usually Matters

Most banks and brokerages won’t stamp for walk-ins. Bank of America, for example, provides medallion services at no charge to clients who have held an account for at least six months.⁴ Smaller credit unions often waive the fee entirely for members. Institutions that do charge typically ask between $10 and $50.

Some member institutions will serve non-customers, though they tend to charge more and look harder at documentation. Fees for non-customers typically run $10 to $50 at a bank or credit union, and third-party services may charge $50 to $100 or more.⁵

Remote and Online Services

The guarantee has traditionally meant an in-person visit, but at least one online service now processes medallion stamps remotely through the STAMP program. The Securities Transfer Association lists eSignatureGuarantee as an option for shareholders inside the United States.⁶ You create an account, verify your identity through the service’s platform, submit your transfer documents, and receive the stamped original back by courier. Useful if nothing nearby participates.

When You Have No Obvious Institution to Ask

Inheriting securities from a relative you never shared a bank with, or holding an old paper certificate from a company you lost touch with years ago, can leave you with nowhere obvious to start. If several local calls go nowhere, contact the transfer agent or issuing company directly. They handle this constantly and can sometimes point you to a participating institution in your area or accept an alternative form of verification.

If You Live Outside the United States

Holding U.S. securities from abroad makes this harder. You may be able to get a guarantee from an overseas branch of a U.S. or Canadian bank, broker, or credit union where you already do business.² The Securities Transfer Association also lists third-party services that provide medallion stamps to shareholders in the United Kingdom, Australia, and other Asia-Pacific countries through STAMP.⁶

For certain U.S. Treasury securities, federal regulations allow alternative certifying individuals outside the country, including U.S. diplomatic or consular officials and officers of foreign branches of institutions that participate in a recognized signature guarantee program.⁷ If none of that fits, call the transfer agent and ask what they’ll accept.

What to Bring to the Appointment

Showing up without the right paperwork is the fastest way to waste a trip. Before you go:

Valid government photo ID (passport or driver’s license) for every person whose signature will be guaranteed.⁴
Proof of ownership: original stock certificates, a recent brokerage statement showing the holdings, or similar documentation.
The unsigned transfer documents. Do not sign anything in advance. The guarantor has to witness your signature in person.
If you’re not a U.S. resident, bring additional proof of address and any related transfer documents.⁵

Acting for an estate? Bring certified copies of the letters testamentary or letters of administration from the probate court. Trustees should bring the sections of the trust agreement that grant authority to manage and transfer assets. Many transfer agents want these recently dated, so copies you picked up months ago may be rejected as stale. If that happens, you’ll need fresh certified copies before trying again.

Check the Stamp’s Dollar Coverage Before You Pick an Institution

Every medallion stamp carries an alpha prefix that tells the transfer agent how much coverage sits behind it. The letter matters because a local credit union’s stamp may not cover a large transaction:

Prefix E or F: up to $100,000
Prefix D: up to $250,000
Prefix C: up to $500,000
Prefix B: up to $750,000
Prefix A: up to $1,000,000
Prefix X: up to $2,000,000
Prefix Y: up to $5,000,000
Prefix Z: up to $14,000,000

If your transfer exceeds the stamp’s limit, the transfer agent will reject it and you’ll have to start again at a different institution. Larger banks and brokerage firms tend to carry higher-tier stamps, so for a sizeable estate or portfolio, ask about the prefix level before you book the appointment.

Can a Notary Do It Instead?

No. A notary confirms that the person signing is who they claim to be, and that’s where the notary’s responsibility ends. A medallion signature guarantee goes further: under UCC Section 8-306, the guarantor warrants that the signature is genuine, that the signer is the right person to authorize the transaction, and that the signer has legal capacity to do so.⁸ If any of those warranties fail, the guaranteeing institution is on the hook financially. A notary carries no comparable obligation, which is why transfer agents won’t accept a notarized signature in place of a medallion guarantee.³

Brokerage account sales are the other common exception people ask about. If your securities already sit inside a brokerage account and you’re simply selling them through that same broker, you typically don’t need a medallion guarantee, because the broker verifies your identity through its own systems. The requirement kicks in when assets move across institutional lines or change registered ownership.²

If You Get Turned Down

Institutions refuse guarantee requests regularly, and they don’t always explain why in detail. The usual reasons: you’re not a customer, your transaction exceeds the institution’s stamp coverage, or something in the documentation raised a flag. Internal compliance rules give the officer wide discretion.

Try a different institution. A brokerage firm where you hold an account may say yes where a bank branch said no, or vice versa. If several refuse, look harder at your paperwork: confirm the ID is current, the proof of ownership matches the exact registration on the securities, and estate or trust documents are recently certified. For persistent problems, the SEC recommends contacting the transfer agent or issuing company directly for help finding a participating institution.²

Federal regulations also prohibit transfer agents from rejecting a guarantee solely because the guaranteeing institution is a particular type of eligible institution, such as a credit union rather than a bank.¹ If a transfer agent rejects your stamped documents on that basis rather than a legitimate coverage or compliance concern, you can raise the issue with the SEC.

1
eCFR. 17 CFR 240.17Ad-15 – Signature Guarantees
2
U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities
3
Securities Transfer Association. STAMP Medallion Guarantee
4
Bank of America. Medallion Signature Guarantee
5
PNC. What Is a Medallion Signature Guarantee and How Do You Get One?
6
Securities Transfer Association. Medallion Guarantee
7
eCFR. 31 CFR 306.45 – Certifying Individuals
8
LII / Legal Information Institute. UCC 8-306 – Effect of Guaranteeing Signature, Indorsement, or Instruction