The Athens Stock Exchange (ASE) on Monday fell by 22.87 percent as trading resumed after a five-week closure.
The four main banks of Greece - Piraeus Bank, National Bank, Alpha Bank, and Eurobank - were all down by around 30 percent, BBC reported.
The ASE plunged to 615.16 points, down 182.36 points since it was shut down on June 26 as the country plunged into an economic crisis.
Prior to the reopening, traders predicted sharp losses as a result of pent-up trading.
The European Commission expects Greece to go back into recession this year, with the economy contracting by between two percent and four percent.
The Greek economy was in recession for six years until 2014.
