The Athens Stock Exchange fell by 22.87 percent on Monday as trading resumed after a five-week closure.
The country's top four lenders, Piraeus Bank, National Bank, Alpha Bank, and Eurobank, were all down by about 30 percent.
The bourse was shut just before Athens imposed capital controls during the peak period of the debt crisis.
Traders had predicted sharp losses as a result of pent-up trading but not long after the resumption today morning, the Athens Stock Exchange plunged to 615.16 points, down by 182.36 points from the June 26 close.
The local Avgi newspaper has reported that Greece is asking for about 10 billion Euros this month for this purpose.
Banks account for about a fifth of the main Athens index.
Banks in Greece are not expected to report a profit this fiscal, as they are suffering from an increase in bad loans due to the crisis.
Greece has presently struck a bailout deal with its creditors, but political in-fighting in Athensover the conditions attached to the deal, could still result in Tsipras calling for an early election.
The Greek economy has been in recession for six years.
