Can Irrevocable Stock Powers be signed in blank (to collateralize a loan) and still be able to be signature guaranteed under a Medallion signature guarantee program? I have been told that Irrevocable Stock Powers cannot be signed in blank and still be qualified to have the customer's signature guaranteed. It has been common practice to have the customer sign the Irrevocable Stock Powers in blank (which are stored separately from the stock) to facilitate possible future liquidation if the related loan becomes uncollectible. What are other shops doing in order to comply with a signature guarantee program if the signature cannot be guaranteed unless the customer is present at the signing of the stock power and the current value of the stock is documented at some time in the future when the liquidation might occur? If signed in blank at time of loan closing the customer will not be present at a future date if the stock were to be come liquidated, thus disqualifying a signature guarantee.