French investment bank Credit Agricole's research analysts said EU leaders had set the expectations bar very low for the summit "and yet they managed to disappoint nervous markets."
Shares on the Athens Stock Exchange hit a new 22-year low Thursday, closing down 4.53 percent despite gains made elsewhere in Europe.
There are concerns among investors that uncertainty over Greece's future in the eurozone could spark a run on the country's banks, further destabilizing the already-shaky banking system and pushing the country even quicker towards a chaotic exit from the currency.
Greeks have been steadily withdrawing deposits in recent months. Bank of Greece figures show that total household and business deposits stood at about €165 billion ($207.2 billion) in March 2012, compared to €235 billion ($295.1 billion) in October 2009, just before the crisis broke. Meanwhile some €700 million ($879 million) were withdrawn in the week following the inconclusive May 6 election.
The summit also addressed the issue of whether the risk inherent in some countries holding so much debt should be spread across the entire eurozone — issuing so-called "eurobonds." This would mean every country could borrow funds at the same rate, substantially lowering the costs for the more indebted countries. French President Francois Hollande wants the bonds to finance growth projects and ease concerns about weaker countries' debt, but Germany's Angela Merkel refuses to consider such an option.
"It would have been great news," said Oscar Moreno of Madrid brokerage Renta4. "It would have been good if there had at least been agreement to study it. It would have calmed things down and been a very preliminary first step to the idea of a Eurobond. But we got nothing."
Economists say eurozone leaders have to find another way to increase its defenses than offering bailout after bailout to its debt-stricken memebers. Javier Diaz-Gimenez, a professor of economics at IESE Business School in Madrid, said that the eurozone needs a fundamental redesign.
"The solution has to be some change in design," Diez-Jimenez said. "Something that says, 'OK, these were the things that were missing.
"Just staggering on, that is not going to work. If you keep staggering on, you are eventually going to fall."
Woolls and Ciaran Giles contributed to this report from Madrid.
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