The benchmark Colombo All Share Price Index fell 19.10 points to 5,494.54 and the S&P SL 20 Index fell 13.90 points (-0.47 percent) to 2,974.15 points.
Turnover was 138 million rupees, the lowest since July 09, when daily turnover fell to 125.1 million rupees, according the Colombo Stock Exchange data.
Sri Lanka's ruling coalition started the process to impeach the country's chief justice Thursday as a stand-off between the judiciary and the legislature worsened.
Dialog Axiata, an telecom firm rose 40 percent to close at 8.40 rupees after posting strong profits, with a tax reversal and foreign exchange gains helping.
Dipped Products, an exporter of rubber gloves rose 7.00 rupees to close at 107.00 after posting better results, partly helped by recent currency depreciation. Haycarb, another export firm closed at 176.40 up 9.90.
People's Leasing and Finance, the country's largest non-bank lender rose 10 cents to close at 12.50 though profits and loan growth was flat.
Hatton National Bank fell 7.20 to close at 140.80 rupees, Commercial Bank closed at 102.90 down 2.0 rupees.