The benchmark Colombo All Share Price Index (ASPI) was down 0.06 percent (1.55 points) to close at 2,625.45 while the Milanka index of liquid stocks gained 0.30 percent (9.01 points) to close at 2,978.77, according to provisional stock exchange data.
Turnover was 685.0 million rupees.
There will be no trading Friday because of a religious holiday.
Brokers said retailers bet heavily on Seylan Bank non-voting, a unit of troubled Ceylinco Group with 7.32 million shares changing hands. It closed at 12.25 rupees, up 25 cents.
Blue Diamonds Jewelry Worldwide non-voting, another unit of the Cneylinco Group closed at 70 cents, up 20 cents.
Another 3.2 million Blue Diamonds Jewelry Worldwide ordinary shares closed at 3.10 rupees, up 1.30.
Environmental Resources Investments (formerly Walker & Grieg) was heavily traded. Warrant 001 closed at 29.75 rupees, up 1.50 with 1.04 million traded. Warrant 002 closed at 30.75 rupees, up 1.75 with 1.51 million traded.
Environmental Resources Investments ordinary shares closed at 42.25 rupees, down 1.00 with 380,900 shares traded.
Hatton National Bank closed at 144.00 rupees, up 4.00, while Distilleries Company of Sri Lanka closed at 81.50 rupees, down 75 cents.
Index heavy conglomerate John Keells Holdings closed at 135.25 rupees, down 25 cents, while Commercial Bank of Ceylon closed at 151.25 rupees, up 25 cents.
Celco Dialog Telekom closed at flat at 5.75 rupees, while fixed line operator Sri Lanka telecom closed flat at 41.00 rupees.