What are the regulatory criteria for assets that are not allowed to be held in an ISA*
*With exception to REITs, which Iβm aware FT is working on.
As someone who not only works in financial services, but works in the stocks and shares industry Iβm well aware of the varying degrees of regulations.
Itβs more for curiousity and to gain a better understanding.
The main concept as it pertains to Freetrade is recognised exchanges. The underlying asset (not the security itself) must be a listed on a recognised exchange. This means an ADR/GDR is valid only if the underlying shares are valid (i.e. listed on an exchange recognised by the UK gov).
As @Cameron says above, it depends on whether the underlying security is traded on a HMRC-recognised exchange. Lots of ADRs are actually Isa eligible, Swiss pharma company Novartis (NVS) is one example.