A medallion signature guarantee is a stamp from a bank, brokerage, or credit union certifying that a signature on a securities transfer document is genuine and that the signer has legal authority to move the assets. SEC Rule 17Ad-15 lets transfer agents require it, and most will not process an ownership change without one.1GovInfo. 17 CFR 240.17Ad-15 – Signature Guarantees The stamp exists because it shifts liability: if the signature later turns out to be forged, the guaranteeing institution absorbs the loss, not you and not the transfer agent.
When You Need One
The guarantee is generally required whenever the ownership or registration of securities changes hands. That covers transferring stock or bond certificates to another person, moving securities into or out of a trust, re-registering an account after the owner dies, and adding or removing a name on a brokerage account. Redemptions and distributions above a certain dollar amount also trigger it, though the threshold varies by institution.
You usually do not need one for routine trades inside your own brokerage account, since the firm already verified you when you opened it. Some brokerages waive the requirement for transactions handled in person at their offices.
Who Can Issue It
Under Rule 17Ad-15, only an “eligible guarantor institution” can provide the stamp: banks, brokers, dealers, credit unions, savings associations, national securities exchanges, and clearing agencies.1GovInfo. 17 CFR 240.17Ad-15 – Signature Guarantees Eligibility alone isn’t enough. The institution must also belong to one of three recognized medallion programs:
- Securities Transfer Agents Medallion Program (STAMP), the largest, with more than 7,000 participating U.S. and Canadian institutions.
- Stock Exchanges Medallion Program (SEMP), covering regional stock exchange member firms, clearing companies, and trust companies.
- New York Stock Exchange Medallion Signature Program (MSP), covering NYSE member firms.
Not every branch of a participating institution keeps the stamp on site. Many banks offer the service only at certain locations or by appointment with a specialist. Call ahead and confirm the branch participates in one of the three programs and can handle your transaction value.2U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities
Most institutions will only guarantee a signature for an existing customer, often requiring at least six months of account history. If you don’t already bank or invest with a participating institution, expect to be turned away. The SEC advises that your best source is a bank, brokerage, or credit union where you already have a relationship.2U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities
How It Differs From a Notary
People confuse these constantly, and the confusion costs wasted trips. A notary verifies that you are the person who signed a document. A medallion guarantee does that and also confirms you have legal authority to transfer the securities, and the guaranteeing institution accepts financial liability if the signature is forged. A notary carries no financial responsibility.
Because a medallion guarantee is not a notarial act, it falls outside state notary law. It is governed by the rules of the medallion programs and SEC regulations. Transfer agents will reject a notarized document when they require a medallion guarantee. The narrow exception is Treasury securities, where TreasuryDirect sometimes accepts a notary’s signature certification, but only when the form specifically says so.3TreasuryDirect. Signature Certification
What to Bring
Incomplete paperwork is the most common reason people leave without a stamp. Gather everything before the visit, because the guaranteeing officer cannot stamp a document that isn’t fully in order.
Every person whose signature will be guaranteed must appear in person with valid, government-issued photo ID. Bring proof of ownership of the securities, such as a recent account statement or the physical stock certificate, showing the security name, account number, and current value. The transfer form should be completely filled out but left unsigned. You sign it in front of the officer.
If the transfer involves a change of ownership beyond a simple sale, you’ll need additional documents 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 enough. 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 agreement that specifically lists the account or securities being transferred, including the account number and firm name.
The institution may also ask for a statement from the receiving account so it can confirm the transfer details match on both ends. If you’re depositing physical stock certificates using a stock power form, bring the stock power rather than expecting to sign the certificate itself.
Transaction Value Limits
Every medallion stamp carries a surety bond that caps the guaranteeing institution’s liability. The stamp’s alpha prefix tells the transfer agent what that ceiling is, and if the market value of your securities exceeds it, the guarantee will be rejected as invalid.
Common prefix tiers:
- 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
This is where large transfers get complicated. Many local branches carry only D or C prefixes, so a $600,000 stock transfer will not clear a D-level stamp. Ask the institution what prefix its 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, multiple guarantees from different institutions each covering a portion of the total value.
The Visit and Timeline
Once the officer reviews your ID and supporting documents, the actual stamping is quick. You sign the form in the officer’s presence, the officer verifies your signature against your ID, and the stamp goes on the signed document. The stamp carries a unique identification number and the alpha prefix showing the surety limit.2U.S. Securities and Exchange Commission. Medallion Signature Guarantees: Preventing the Unauthorized Transfer of Securities
Turnaround depends on the institution and the complexity of the transaction. Branches with a stamp on site can sometimes finish straightforward requests the same day if the paperwork is in order. Complex cases involving estate documents or entity transfers may take two to five business days for internal review before the stamp is applied. Ask whether same-day stamping is available.
There is no formal expiration date on the guarantee itself, but some transfer agents have internal policies on how old a stamped document can be when submitted. Send the paperwork to the transfer agent promptly.
Fees
Most banks and brokerage firms provide medallion signature guarantees at no charge to their existing customers. Institutions treat it as a relationship benefit rather than a revenue line. If a fee applies, it is usually modest and 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 tend to charge significantly more.
Why Requests Get Denied
Getting turned away is common, and the reasons repeat:
- No existing account relationship. Most institutions require at least six months of history. Walking in as a non-customer almost never works.
- Missing or stale legal documents. Old Letters Testamentary, a will without court appointment documents, or a power of attorney that doesn’t specifically cover securities transactions will all draw a rejection.
- The transfer form was signed before the visit. The whole point is that the officer watches you sign. If you signed at home, you need a fresh form.
- The transaction exceeds the stamp’s limit. If the branch’s prefix cannot cover the market value, the officer cannot proceed.
- Mismatched information. If the name on your ID doesn’t exactly match the name on the account, or the transfer details don’t align between sending and receiving accounts, expect delays or denial until it’s resolved.
The guaranteeing institution takes on real liability when it stamps, so caution is built into the process. If you’re denied, ask exactly what’s missing so you can come back prepared.
If You Live Abroad
This is one of the hardest situations in the whole securities transfer process. U.S. embassies and consulates do not provide medallion signature guarantees. The State Department has said explicitly that consular and foreign service officers are not authorized to perform the service, because only financial institutions in an SEC-recognized medallion program can affix the stamp.4U.S. Department of State. Medallion Signature Guarantee Information
The State Department suggests contacting local branches of U.S. banks or brokerages that operate in your country. Some major U.S. institutions with international offices may be able to help, but availability is inconsistent. You can also contact the transfer agent or issuer directly. Some transfer agents have processes for overseas shareholders that use alternative verification, such as notarization combined with additional documentation, though acceptance varies.
If You Can’t Get One
If you’ve been turned away by multiple institutions, the SEC recommends contacting the transfer agent or the issuer 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 and may accept alternative authentication when a shareholder genuinely cannot obtain a medallion stamp. Alternatives some agents use include phone verification with the shareholder of record, electronic identity verification through security questions, or notarization paired with supplemental legal documentation.
None of these alternatives carry a surety bond, so transfer agents are reluctant to use them for high-value transactions. For smaller transfers, or where identity isn’t genuinely in doubt, the agent may work with you. Contact them early rather than spending weeks chasing a stamp no institution will give you.