The Milanka Index closed down 2.65 points at 3,458.77.
The market sank lower towards the end of trading with no positive economic or political news to help keep it afloat, stockbrokers say.
Speculators were dabbling in lesser known stocks, brokers said.
John Keells Holdings' shares closed up one rupee at 133.50. Over a million shares of the conglomerate were traded adding over 133 million rupees to turnover.
Sri Lanka Telecom closed up 25 cents at 34.25 rupees while Dialog Telekom closed flat at 22.50 rupees.
Walker and Greig, an old established distribution firm which had several agencies including the Gillette brand closed up 1.75 rupees at 23 trading over two million shares. The firm has been running losses and is a shell company that has been bought by a foreign firm.
The rupee closed at 113.28/34 against the spot dollar with some dollar buying by state n