The SOFIX, which comprises the 20 most liquid shares trading on the Bulgarian Stock Exchange (BSE), added 2.23% to 457.82 points and the broader BG40 index, which tracks the 40 most traded shares on the bourse, gained 1.44% to 126.32 points.
The SOFIX rose 2.33% and the BG40 advanced 3.69% on Thursday.
Turnover, excluding block and other pre-agreed deals, increased to 2.3 million levs ($1.7 million/1.2 million euro) from 1.1 million levs a day earlier. Trade in Avto Union bonds accounted for 1.0 million levs of Friday's turnover.
Avto Union has a 7.5 million euro ($10.7 million) bond listed on the BSE.
Earlier in the day, the company said it plans to issue five-year convertible bonds.
Avto Union's parent, financial and insurance group Eurohold Bulgaria, was also among the most liquid issues on Friday. Its stock gained 2.53% to 1.83 levs in a volume of 38,300 shares.
On Friday, 56 stocks advanced, 15 fell and 11 closed unchanged.
All of the bourse's blue chips were traded during the session. Two ended lower and one was unchanged.
Fuel and building materials retailer Toplivo led the blue-chip charge, surging 11.11% to 5.0 levs in a volume of 2,287 stocks.
The BG-REIT index, tracking the performance of real estate investment trusts, rose 1.5% to 44.77 points after adding 0.25% on the previous day. The bourse's BG TotalReturn30 index, in which companies with a free float of at least 10% have equal weight, ended 2.69% higher at 341.26 points. The BG TotalRetur 30 picked up 3.26% a day earlier.
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, climbed 2.1% to 66.11 points.
(1 euro = 1.95583 Bulgarian levs)