Is there any law or regulation that would prevent trust preferred stock from being used as collateral for a consumer loan?

We are unaware of any express prohibition against using trust preferred stock as collateral for a loan, provided that the trust preferred stock has not been issued by the lending bank or its affiliate.  Trust preferred stock is a security, and we are unaware of any rationale why it would be treated differently than other types of securities for purposes of pledging the security as collateral for a loan.