... shall be [properly] registered by the issuer's registrar (custodian). Something to that effect anyway, and you also need to look at where this gem is going since they call these things different name in different places. In the US, we do not generally "pledge" securities and such but rather use them as security/to secure debt. The bank maintaining your shareholder register is usually called a custodian or transfer agent (there's actually a difference btw the two but what they do overlaps to a large extent). Elsewhere, it may be called a registrar.

Overall, this remarkable formulation is just about as far from the way such things are phrased in the US as one could imagine, and most of the original verbiage would be superfluous since pretty much all shares of stock these days are registered (imenniye) and no one gives a hoot about how exactly the custodian goes about maintaining the records (well, duh, they use a software package run by computers ("system") for maintaining the shareholder register).

Then again, depending on what your client expects, instead of giving them a sensible natural-like rendering of this gem, you may want to say "a system for maintaining the register of holders of registered shares through an account with a custodian bank". See for yourself which way you'll be better off. Cheers, Angela.