Is that because the people making the loan aren't sophisticated enough to price those securities correctly in this context and so are being taken advantage of?
> a popular kind of financial engineering among very wealthy people
To use assets without a single universal price as collateral? I think everyone does this.
No, it's because using stock (and other securities) this way allows them to "convert" the stock into money without actually realizing the gains. Thus they derive benefit from the gains without actually paying capital gains tax.
They're deriving secondary benefit from ownership and they're paying interest for the facility with the ultimate expectation that they pay back the loan and the stocks never actually trade hands.
This is not much different from any interest bearing account. Should it be that you have to take all your money out of savings and ensure you earn nothing from it if you intend to offer it as collateral on a loan?
The difference is taxes. Interest on a savings account used as collateral is still taxed. Gains used as collateral in a loan are not taxed.
The parent poster is suggesting this loophole be closed - that the practice either be disallowed or considered realizing the gains for tax purposes.
Obviously I am over-simplifying a little, but this is a real thing. Here's a more comprehensive explanation: https://smartasset.com/investing/buy-borrow-die-how-the-rich...