Some of Greece's biggest banks may have to shut and merge with their rivals, it has been claimed.
A European official told the Reuters news agency that Greece's four big banks - National Bank of Greece, Eurobank, Piraeus and Alpha Bank - could be reduced to just two.
European leaders are meeting on Sunday in a bid to strike a financial aid deal with Greece.
The banks aren't open today and it seems very unlikely they're going to open tomorrow.
The money taps have been turned off by the European Central Bank and until they get switched back on again, the Greek banks cannot open.
But you can't run a major economy when people can't get money out of the banks, when firms can't pay people because they can't do bank transfers, when companies can't pay for goods or imports.
If those money taps aren't turned back on by the ed of the week and the banks aren't re-opened, Greece will have to start producing some form of alternative currency - even if they don't call it the Drachma.
The Greeks have voted to reject the austerity terms demanded by eurozone creditors - so, what happens next?
Greeks have voted to reject the terms of an international bailout, putting it on the brink of a eurozone exit.
Greece's controversial Finance Minister Yanis Varoufakis has released a defiant statement of resignation entitled 'Minister no more!'