The SOFIX index, which comprises the 20 most liquid shares trading on the Bulgarian Stock Exchange (BSE), dropped 2.07% to 434.91 points. The broader BG40 index, which tracks the 40 most traded shares on the bourse, closed 1.95% down at 118.43 points.
On Wednesday, the SOFIX was up by 0.81%, while the BG40 rose by 0.79%.
Stock turnover, excluding block and other pre-agreed deals, rose to 1.28 million levs ($0.97 million/0.65 million euro) from 680,000 levs on Wednesday.
On Thursday, 47 stocks declined, 20 rose and 9 closed unchanged.
Eighteen of the 20 blue chips were traded on Thursday with three gaining ground, one closing flat and the rest moving lower.
Bulgarian paint producer Orgachim led the SOFIX decliners, shedding 7.1% to 83.60 levs with just 20 shares changing hands.
Central Cooperative Bank was the most liquid blue chip with a turnover of 330,617 levs on Thursday, closing 3.75% lower at 1.386 levs, followed by First Investment Bank and equity financing and insurance group Eurohold Bulgaria.
The BG-REIT index, which tracks the performance of real estate investment trusts, backed off 0.97% to 46.75 points after a drop of 0.3% on Wednesday. The BG TotalReturn30 index, in which companies with a free float of at least 10% have equal weight, lost 1.44% after an advance of 0.37% on Wednesday.
The Dnevnik 20 index, calculated by local business daily Dnevnik from the share prices of the 20 leading companies in terms of liquidity and market capitalisation, fell 1.96% to 62.64 points on Thursday after retreating 0.23% a day earlier.
(1 euro = 1.95583 Bulgarian levs)