[hfttrader]

But why does transferring large amounts of dollars take days? There is nothing physical preventing banks from supporting fast transfers. They can do fast transfers with BTC or USD.

Transfers are slow because there is little need to transfer large amounts of money quickly, and slower transactions help address issues with fraud. If you are buying a car, or paying for a house there is little need for a fast transactions. So with BTC or USD, transferring large amounts of money will take days.

[mike_hearn]

It's got nothing to do with fraud checks. Transfers take days because banks largely run on mainframes programmed in the 1970s. Because of the (by todays standards) peculiar designs those machines had, the bulk of the work is done at night in batch jobs. The vast size and complexity of the software, combined with archaic platforms, their business-critical nature, and almost total absence of competition means that banks don't upgrade to more modern systems unless forced (see the UK same day payments initiative). Then the banking network is not a perfectly connected system so sometimes payments must be routed via intermediate banks. That's why it can end up taking days.

[natrius]

Good point. I think the debit card replacement angle is much more attractive than this one.