The Colombo All Share Price Index closed down 0.
35 percent (15.47 points) to end at 2,185.00 while the Milanka index of liquid stocks gained 0.
98 percent (24.07 points) to close at 2,441.60, according to provisional stock exchange data.
Turnover was 293.3 million rupees.
"The market opened positively but lost ground mainly due to price drops on index heavy stocks such as Commercial Bank, Sri Lanka Telecom (SLT) and Distilleries," said Dharshi Ganeshan of Bartleet Mallory Stockbrokers.
"SLT and Commercial Bank were down owing to profit taking."
Distilleries Company of Sri Lanka which lost a court case last Thursday to retain ownership of subsidiary Sri Lanka Insurance Company (SLIC) lost 3.75 rupees to close at 77.75.
Distilleries, a spirits manufacturer, paid six billion rupees to acquire SLIC from the Sri Lankan government in 2003. SLIC is now back under government ownership.
Sri Lanka's largest privately held bank, Commercial Bank of Ceylon, lost 3.00 rupees to close at 123.00, while fixed line giant SLT lost 1.50 rupees to close at 41.50.
"Retail participation was high today," said Ganeshan.
Conglomerate John Keells Holdings closed flat at 112.
00 rupees.
Diversified Hayleys gained 25 cents to close at 115.25, while privately held bank, Hatton National Bank, lost 1.
25 rupees to close at 113.00 on thin volumes.
The spot dollar remained unchanged at 114.
90/95 levels in late afternoon trade, dealers said.
Foreigners brought 20.5 million rupees worth of shares and sold 53.5 million rupees worth, resulting a net outflow of 33 million rupees.