The blue-chip SOFIX index which includes the 20 most liquid stocks on the Bulgarian Stock Exchange (BSE) rose 4.91% to 334.69 points and the broader BG40 index which tracks the 40 most traded shares on the bourse, surged by 6.78% to 98.75 points by 1000 GMT.
A day earlier the SOFIX dropped 5.35% to 319.04 points and BG40 slid 5.20% to 92.48 points.
Turnover stood at 1.4 million levs ($898,000/716,000 euro) by 0900 GMT. BSE's turnover totalled 27.8 million levs on Thursday, lifted by trading in blue-chip fuel retailer Petrol.
The BG TotalReturn30 (BG TR30) index, in which companies with a free float of at least 10% have equal weight, advanced 4.51% to 265.05 points by 1000 GMT after sagging 5.74% to 253.62 points a day ago.
(1 euro=1.95583 Bulgarian levs)