The blue-chip SOFIX index, which tracks the 15 most liquid shares on the Bulgarian Stock Exchange (BSE), closed 2.92% higher at 341.28 points after rising by 0.18% on Friday.
The bourse was closed on Monday, Tuesday and Wednesday for the Christmas holidays.
The broader BG40, which includes the 40 most traded shares, was up 0.41% to 123.91 points after losing 0.17% in the previous trading session.
Total turnover on the regulated market dropped to 1.4 million levs ($947,000/716,000 euro) from 10.48 million levs on Friday, when it was boosted by trading in shares of Balkan and Sea Properties REIT [BUL:5H4].
Nine of the 14 SOFIX components which were traded on Thursday rose, three fell and two ended flat.
Mineral extracting and processing company Kaolin [BUL:6K1] was the top SOFIX gainer, closing 18.97% higher at 3.1 levs as 32,912 shares changed hands.
Industrial group Chimimport [BUL:6C4] led the blue-chip decliners, ending 5.95% lower at 0.79 levs as 16,987 shares changed hands.
The BG-REIT index, which tracks the performance of real estate investment trusts, ended 1.92% higher at 80.29 points after declining by 0.39% on Friday.
The BG TotalReturn30, in which companies with a free float of at least 10% have equal weight, lost 0.06% to 256.23 points after rising by 0.65% in the previous trading session.
The CGIX Corporate Governance index, which includes companies strictly applying corporate governance principles, ended 1.94% higher at 76.74 points. It gained 0.55% on Friday.
(1 euro = 1.95583 Bulgarian levs)