Shares on the Athens Stock Exchange have fallen sharply for the third day on the risk of a snap general election in Greece.
The Athens general share index fell more than 7.5% on Thursday.
Greece has brought forward to this month the date of its next presidential election, which is decided by its parliament.
A general election will take place if the government's nomination is not approved by parliament.
On Thursday an official in the governing coalition said it was still short of the support needed to stop the government collapsing in the parliamentary vote.
Despite recently emerging from recession, Greece was thrown back into uncertainty this week, when conservative Prime Minister Antonis Samaras called an early vote in parliament to elect a new president - despite requiring support from opposition politicians to avoid a stalemate.
The announcement on Tuesday came after eurozone ministers approved a Greek request for a two-month extension to its bailout programme, due to end later this month.
The presidential vote on 17 December will be a vital test for Mr Samaras.
His conservative-led coalition needs the support of other parties if its candidate is to obtain the backing of MPs.
But the left-wing anti-bailout Syriza party is leading in the opinion polls and the government faces widespread public discontent after a six-year recession.
Mr Samaras' decision prompted the stock market in Athens to plummet 9.5% on Tuesday.