I don't think this kind of situation could occur in the US because rehypothecation of shares underlying ETFs isn't allowed. See also https://www.bogleheads.org/

I don't think this kind of situation could occur in the US because rehypothecation of shares underlying ETFs isn't allowed. See also https://www.bogleheads.org/wiki/Vanguard_safety https://www.bogleheads.org/wiki/Vanguard_safety And worst case if something did happen it would be bailed out.