The banking industry has described its agreement with Greece to cut its debts as "unprecedented".
A group of banks and other investors in Greek government debt have agreed to exchange their debt for new bonds that are worth much less and pay a modest rate of interest.
Including the reduced interest rate, the losses to the banking industry are more than 70%.
For some of Europe's biggest banks, that means heavy losses.
"The losses are going to be substantial, but they are contained and there's a longer-term benefit for the system in having a core group of investors sit down across the table and coming together," said Charles Dallara, managing director of the Institute for International Finance, which negotiated on behalf of the banking industry. Continue reading the main story ?Start Quote
In the long and tawdry history of governments borrowing more than they can afford, this represents a remarkably huge, unprecedented write-off?
image of Robert Peston Robert Peston Business editor, BBC News
More from Robert
It is perhaps no great surprise that Greek banks are the most exposed to Greek debt.
According to Barclays Capital, the top two holders of Greek debt are National Bank of Greece, with 13.2bn euros ($17.5bn), and Eurobank EFG, which holds 7.3bn euros ($9.7bn).
Once the bond exchange is completed, those holdings will be worth less than half their current value, and if you include future interest payments, worth 70% less.
Outside Greece, French and German banks hold the most Greek debt. The last bailout?
Many foreign banks have already accepted that their investments in Greece are now worth just a fraction of their original value, irrespective of the latest deal.