A Medallion Signature Guarantee is a stamp from a bank, broker, or credit union certifying that the signature on a securities transfer document is genuine and that the signer has legal authority to move the securities. Federal securities regulations under SEC Rule 17Ad-15 require transfer agents to set standards for accepting these guarantees, and most will not process an ownership change without one.1GovInfo. 17 CFR 240.17Ad-15 – Signature Guarantees The stamp shifts financial liability: if the signature later turns out to be forged, the institution that stamped the document bears the loss, not you and not the transfer agent.
When You Need One
The stamp is generally required whenever you change the ownership or registration of securities rather than simply trading within your own account. Common triggers include transferring stock or bond certificates to another person, moving securities into or out of a trust, re-registering an account after an owner’s death, and adding or removing a name on a brokerage account. Redemptions or distributions above a dollar threshold set by the institution also trigger the requirement.
Routine buys and sells inside your existing brokerage account do not need a guarantee, because the firm already verified your identity when you opened the account.
Where to Get the Stamp
Under SEC Rule 17Ad-15, only an “eligible guarantor institution” can provide the guarantee. That category includes banks, brokers, dealers, credit unions, savings associations, national securities exchanges, and clearing agencies.1GovInfo. 17 CFR 240.17Ad-15 – Signature Guarantees The institution also has to belong to one of three recognized Medallion programs: the Securities Transfer Agents Medallion Program (STAMP), which covers more than 7,000 U.S. and Canadian institutions; the Stock Exchanges Medallion Program (SEMP); or the New York Stock Exchange Medallion Signature Program (MSP).
Two practical constraints narrow the field further. First, not every branch of a participating institution has the stamp on site; many banks keep the service at specific branches or require an appointment with a specialist. Second, most institutions will only guarantee a signature for an existing customer, often requiring at least six months of account history. The SEC itself advises that your best source is a bank, brokerage firm, or credit union where you already do business.2U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities Call ahead and confirm both program participation and that the branch can handle your transaction value before making the trip.
A Notary Is Not a Substitute
This is the confusion that costs people the most wasted trips. A notary public verifies that you are the person who signed a document. A Medallion Signature Guarantee does that and also confirms your legal authority to transfer the securities, and the guaranteeing institution accepts financial liability if the signature is forged. A notary takes on no financial responsibility.
Because the Medallion Guarantee is not a notarial act, it falls outside state notary laws entirely, and transfer agents will reject a notarized document when they require a Medallion stamp. The narrow exception is Treasury securities, where TreasuryDirect sometimes accepts a notary’s signature certification, but only when the specific form says so.3TreasuryDirect. Signature Certification
What to Bring
Incomplete paperwork is the most common reason people leave without a stamp. Gather everything before your visit, because the guaranteeing officer cannot stamp a document that is not fully in order.
Every person whose signature must be guaranteed has to appear in person with valid, government-issued photo identification. Bring proof of ownership of the securities, such as a recent account statement or the physical certificate, showing the security name, account number, and current value. Fill out the transfer form completely, but leave it unsigned. You will sign it in front of the guaranteeing officer.
If the transfer involves more than a straight sale, additional documents apply based on the circumstances:
- Death of an owner: a death certificate plus court-issued Letters Testamentary or Letters of Administration. A will alone is not sufficient. Letters Testamentary generally must be dated within 90 days of original issuance, so get fresh copies if yours are older.
- Trust transfer: a copy of the trust agreement identifying the trustees and their authority over the securities.
- Power of attorney: the original or a certified copy of the document granting authority over the account.
- Divorce: a court-approved domestic relations order or divorce settlement that specifically lists the securities or account being transferred, including the account number and firm name.
The institution may also ask for a statement from the receiving account to confirm that the transfer details match on both ends. If you are depositing physical certificates using a stock power form, bring the stock power rather than expecting to sign the certificate itself.
Stamp Value Tiers
Every Medallion stamp carries a surety bond that caps the institution’s liability at a specific dollar amount, and the stamp’s alpha prefix tells the transfer agent what that ceiling is. If the market value of the securities exceeds the stamp’s limit, the transfer agent will reject the guarantee as invalid.
- D: up to $250,000
- C: up to $500,000
- B: up to $750,000
- A: up to $1,000,000
- X: up to $2,000,000
- Y: up to $5,000,000
- Z: up to $14,000,000
Many local branches carry only D or C prefixes, so a $600,000 transfer will not clear at a D-level branch. Ask what prefix the stamp carries before you go. For very large transfers, you may need a larger institution with an X or Y prefix, or in some cases you can obtain multiple guarantees from different institutions, each covering a portion of the total value.
At the Visit and After
Once the officer reviews your ID and supporting documents, the stamping itself is straightforward. You sign the transfer form in the officer’s presence, the officer verifies the signature against your ID, and then affixes the physical Medallion stamp, a high-security imprint carrying a unique identification number and the alpha prefix that shows the surety limit.2U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities
Turnaround depends on the branch and the complexity of the transaction. Simple requests at branches with an on-site stamp can sometimes be completed the same day. Estate or entity transfers may take two to five business days for internal review before the stamp is applied. The guarantee itself has no formal expiration date, but some transfer agents have internal policies about how old a stamped document can be, so send it in promptly.
Common Reasons for Denial
The guaranteeing institution takes on real financial liability when it stamps your document, so it has every incentive to be careful. Requests get turned away most often for these reasons:
- No existing account relationship, or an account that has not been open long enough. Walking in as a non-customer almost never works.
- Missing or stale legal documents: outdated Letters Testamentary, a will without court appointment papers, or a power of attorney that does not specifically cover securities transactions.
- A transfer form signed before the visit. The whole point is that the officer watches you sign. If you signed at home, you need a new form.
- Transaction value above the branch’s stamp prefix.
- Mismatched information: the name on your ID does not match the name on the account, or the transfer details do not align between the sending and receiving accounts.
If you are denied, ask exactly what is missing so you can come back prepared.
Fees
Most banks and brokerage firms provide the guarantee at no charge to their existing customers, treating it as a relationship benefit rather than a revenue line. If an institution does charge, expect a modest fee that varies with the complexity and value of the transfer. Third-party services that market to people who cannot get the stamp through their own bank generally charge more.
If You Live Abroad or Cannot Get One
U.S. embassies and consulates do not provide Medallion Signature Guarantees. The State Department has explicitly said consular and foreign service officers are not authorized to perform this service, because only financial institutions in an SEC-recognized Medallion program can affix the stamp.4U.S. Department of State. Medallion Signature Guarantee Information If you live overseas, the State Department suggests contacting local branches of U.S. banks or brokerages that operate in your country. Some transfer agents also have processes for overseas shareholders that combine notarization with additional documentation, though acceptance varies.
If you have been turned away by multiple institutions, the SEC recommends contacting the transfer agent or the issuer that is requiring the guarantee.2U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities Transfer agents have some flexibility in how they verify signatures. Alternatives that some use include phone verification with the shareholder of record, electronic identity verification through security questions, or notarization combined with supplemental legal documentation. None of these carry a surety bond the way a Medallion Guarantee does, so agents are reluctant to accept them for high-value transfers, but for smaller transactions they may work with you. Contact them early rather than spending weeks chasing a stamp no institution will give you.