The main share index edged up 0.09 percent, or 5.20 points, to 5,952.62, hovering near its three-month high hit on Thursday.
'Retail investor participation has not picked up and that has hit the market volume and turnover,' said a stock broker.
Retail investors in the past have accounted for around 60 percent of the market's daily volume, which hit a five-week low of 20.9 million shares.
The day's turnover slumped to 233.3 million rupees, the lowest since July 17 and well below this year's daily average of about 868 million rupees.
Foreign investors were net buyers of 12.2 million rupees ($93,100) worth of shares, extending the net buying so far this year to 21.48 billion rupees.
The banking and finance share index rose 0.74 percent, led by Ceylinco Insurance PLC which rose 4.38 percent.
($1 = 131.0750 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Subhranshu Sahu)
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