The All Share Price Index closed up 0.02 percent (0.54 points) to end at 3,117.10 while the Milanka index of more liquid stocks lost 0.
12 percent (4.31 points) to close at 3,524.71, according to provisional stock exchange data.
Turnover reached 1.63 billion rupees.
There was a net foreign inflow of 40.1 million rupees as foreigners sold 663.1 million rupees worth of shares and bought 703.
4 million rupees, brokers said.
"Despite high turnover levels the market closed flat," said Nikita Tissera, research manager at stock brokering house, SC Securities.
Hatton National Bank closed at 171.
75 rupees, up 1.75 on almost three million shares traded, and Commercial Bank of Ceylon closed at 181.25 rupees, up 1.25.
National Development Bank closed flat at 195.00 rupees, and DFCC Bank closed flat at 152.50 rupees.
Conglomerate John Keells Holdings closed at 154.50 rupees, up 50 cents, while index heavy Distilleries Company of Sri Lankan closed at 90.75 rupees, down 25 cents.
"Retailer favorite stocks, Lanka Cement and Touchwood, were actively traded today," Tissera said.
Lanka Cement closed at 33.25 rupees, up 2.00 with 1.2 million shares traded, and Touchwood Investments closed at 92.25 rupees, down 1.50.
Dialog Telekom a unit of Telekom Malaysia closed at 8.
00 rupees, down 25 cents, and Sri Lanka Telecom 46.75 rupees, up 1.00.