Bulgarian Stock Exchange indices closed higher on Thursday, largely backed by hefty gains of industrial companies and diversified holdings.One of the most notable gainers on Thursday was industrial group Stara Planina Hold, which dropped out of the base of the blue-chip SOFIX index as of September 24. The company gained an impressive 6.80%, closing at 5.50 levs - its highest closing price since August 15.The biggest gainer on the stock exchange on Thursday was aluminum products maker Alcomet, which added 7.53% to close at 10.0 levs.Among blue-chips, diversified groups Doverie United Holding and Eurohold Bulgaria rose most, by 1.20% and 1.06%, respectively. The blue-chip SOFIX index edged up 0.01% to 573.68 points on Thursday.The wider BGBX40 index, which tracks the 40 most traded shares on the Sofia bourse, rose 0.54% to 113.55 points, while the BGTR30 index, in which companies with a free float of at least 10% have equal weight, added 0.56% to 507.56 points.The BGREIT index, which tracks the performance of real estate investment trusts, closed 0.15% higher at 126.55 points. Among BGREIT members, Bulgarian Real Estate Fund REIT gained 0.50%, while Advance Terrafund added 0.26%. Total regulated market trading turnover more than halved to 841,000 levs on Thursday from 1.77 million levs on Wednesday.