The main share index edged up 0.04 percent, or 2.54 points, to close at 5,786.16.
Foreign investors were net buyers of 233.3 million rupees ($1.8 million) worth of shares on Thursday, extending net foreign inflows over the past six days to 1.09 billion rupees.
They have been net buyers of 19.72 billion rupees so far this year.
Shares in Commercial Bank of Ceylon, the largest listed lender in Sri Lanka, rose 1.47 percent to 117.70 rupees, while Carson Cumberbatch PLC gained 5.04 percent to close at 389.90 rupees.
Thursday's turnover was 920.2 million rupees, the highest in two weeks.
($1 = 132.0500 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Prateek Chatterjee)
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