A Greek exit from the euro zone could expose the European Central Bank and the currency bloc it seeks to protect to hundreds of billions of euros in losses, landing Germany and its partners with a crippling bill.
A Greek departure would take Europe into uncharted legal waters. The size of the burden other euro zone states could bear gives them a powerful incentive to keep Greece in the currency club.
With most of Greek's private creditors having taken heavy writedowns as part of the country's second, 130 billion euros bailout, it is estimated that the ECB, International Monetary Fund and euro zone nations hold about 200 billion of its debt.
"In the event of an exit, they (Greece) will default. And the loss given default will probably be very high, high enough to eliminate the ECB's capital," said Andrew Bosomworth, senior portfolio manager at asset manager Pimco.
"They might need recapitalisation from governments, who are not exactly in the best position to provide additional capital."
Those are not the only losses the ECB and its national shareholders might face as is explained in detail below.
Even once Greece had left the currency club, the costs to the rest of the euro zone would continue to mount as it would probably be compelled to avert a complete Greek collapse and wider contagion.
"Large-scale ECB intervention would be necessary to stabilize the system, along with intervention from Germany, the European Stability Mechanism (ESM), its predecessor the European Financial Stability Facility (EFSF) and the IMF, potentially costing hundreds of billions of euros," said Georgios Tsapouris, investment strategist at Coutts.
The ECB, which has its own paid-in capital of 6.4 billion euros, is essentially a joint venture between the 17 euro zone national central banks (NCBs). Combined, the Eurosystem of euro zone central banks has capital and reserves of 86 billion euros.
The national central banks would divide up any losses between them according to the 'capital key' - the ECB's measure of countries' stakes in its financing based on economic size and population. Germany would bear the biggest loss, some 27 percent of the total.
France would take a big hit too.
A Greek exit from the euro zone could cost the French taxpayer up to 66.4 billion euros and saddle the country's banking system with 20 billion euros in lost loans, according to a study published on Tuesday by the IESEG School of Management in Lille.
Smaller countries with less robust national central banks than the German Bundesbank would likely be still harder hit in relative terms.
"The ECB and some of the NCBs with little loss-absorbing capital and reserves relative to their share of how a loss would be allocated across the Eurosystem would potentially see their capital and revaluation reserves written off," Bosomworth said.
However, with fresh Greek elections called for June 17 and an anti-bailout leftist party ahead in the polls, some within the EU's corridors of power wonder whether the show is worth keeping on the road.
"It's going to hurt, absolutely. But is it going to be lethal?" one EU diplomat said. "We have two bad choices, but one is worse than the other."
