Your father’s died, and among the paperwork is a folder of US shares he bought years ago. You write to the transfer agent to sell or move them. Back comes a letter saying the form needs a medallion stamp, and your high street bank has never heard of it. That’s a very common story in UK estate work.
A medallion signature guarantee protects the transfer agent against forged or unauthorised transfers of North American stocks and shares. It’s used for estates, gifts of shares and sale instructions. And it’s hard to get outside North America, which is why so many executors get stuck on this one step.
The detail that catches people out is the value limit. Each guarantee carries a ceiling, and the transfer agent will reject a stamp that doesn’t cover the holding. On 10 August 2026, Lester Aldridge announced it had raised its own capacity to US$1,000,000, which tells you the market is moving towards higher-value holdings. Still, it’s only one provider, and limits differ from one to the next.
So do three things before you send anything. Work out the current market value of the holding in US dollars, not pounds. Ask the transfer agent, such as Computershare, what guarantee level it will accept. Then check that whoever provides your medallion stamp can cover that figure, because a rejected form can add weeks to an estate that’s already dragging.
If you’re stuck at this stage, Medallion Signature can explain what the transfer agent is asking for and what you’ll need to provide. Have a look at https://medallionsignature.co.uk/ or get in touch and ask before you post the forms.
