The SOFIX index, which includes the 19 most liquid stocks on the Bulgarian Stock Exchange (BSE), lost 2.93% to 931.02 points. The broader BG 40 index, which tracks the 40 most liquid companies on the bourse, dropped 2.96% to 227.30.
"The SOFIX lost 4.0% during the first half of the trading session on Monday as news of the Lehman Brothers bankruptcy prompted a broad sell-off," Bulgarian brokerage Elana Trading said in a daily statement.
"The financial storm is weighting on the Bulgarian market despite the moderate trading volumes," it said, adding that liquid shares underperformed.
Banks were among the worst performers, said the brokerage.
The most liquid among the banks - First Investment Bank (FIBank), was the top loser among the lenders, falling 3.26% to 5.9 levs in a volume of 40,318 stocks.
The Central Cooperative Bank ended 1.15% lower at 3.15 levs as 5,265 shares were traded. The Bulgarian American Credit Bank dropped 4.58% to 53.9% after only 89 stocks changed hands. Corporate Commercial Bank was least affected, inching down 0.02% to 91.98 levs in a volume of 1,235 stocks.
Industrial companies and holding groups also lost ground with the exception of Industrial Holding Bulgaria, Elana Trading said. The holding closed 1.22% higher at 5.8 levs as 1,050 shares were traded.
Bulgarian mineral extraction and processing company Kaolin AD was the top loser among the blue chips, falling 5.95% to 6.02 levs as 6,361 shares were traded. Drug maker Sopharma posted the second biggest decline of the day, losing 5.59% to 3.68 levs in a volume of 6.281 shares.
BSE's total turnover, excluding block and other pre-agreed deals, fell to 2.9 million levs ($2.1 million/1.5 million euro) from 7.8 million levs on Friday.
On Monday, fallers led advancers by 79 to 19 and 14 stocks closed flat.
The BG TotalReturn30 (BG TR30) index, in which companies with a free float of at least 10% have equal weight, dipped 3.22% to 608.53 points and the BG-REIT index, tracking the performance of real estate investment trusts, ended 0.83% lower at 83.43.
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, depreciated 4.94% to 118.32 points.
(1 euro = 1.95583 Bulgarian levs)