>My jaded view would be that the banks would just borrow free money
I'm not entirely sure that is how it would work. They use Denmark as an example, but I believe that the negative interest here was for deposits in "National Banken"/treasury bonds. Meaning that the banks can't just park their money with the state, at least not without incurring a lose.
Some still bought Danish treasury bonds, because at least the lose would be predictable and with no real risk.
It forces the banks to actually do something with what ever money they have, but you're right in as so fare that the customers aren't going to benefit. Most likely the money will just be placed in stock or treasury bond of other stable countries.
I'm not entirely sure that is how it would work. They use Denmark as an example, but I believe that the negative interest here was for deposits in "National Banken"/treasury bonds. Meaning that the banks can't just park their money with the state, at least not without incurring a lose.
Some still bought Danish treasury bonds, because at least the lose would be predictable and with no real risk.
It forces the banks to actually do something with what ever money they have, but you're right in as so fare that the customers aren't going to benefit. Most likely the money will just be placed in stock or treasury bond of other stable countries.