The Greek stock market plunged more than nine percent in early trading on Thursday after the European Central Bank moved to restrict Greek banks' access to a key source of cash.
After opening slightly down, the Athex general index slid by 9.43 percent to 768 points, before recovering some of its losses.
Bank shares were down 22.82 percent to 636 points.
Greek 10-year bonds meanwhile were fetching yields of 10.051 percent on the secondary market, up from 9.678 on Wednesday.
In an announcement late Wednesday, the ECB said it would no longer allow Greek banks to use government debt as collateral for loans.
Greek debt has a junk credit rating and, under ECB rules, should not qualify as collateral.
But Greece had been granted a waiver because of the country's dire economic situation -- provided it complied with the terms of its huge bailout.
The hard-left government of Prime Minister Alexis Tsipras, which took office last week, is trying to renegotiate its 240-billion-euro ($270 billion) EU-IMF loans.