The main share index ended 0.06 percent, or 3.16 points up, at 5,688.98.
John Keells Holdings gained 0.63 percent to reach 238.60 rupees.
Foreign investors were net buyers of 261.2 million rupees ($2.07 million) worth of shares, extending year-to-date foreign inflows to 3.43 billion rupees.
Turnover was 609.2 million rupees ($4.82 million), well below this year's daily average of 1.04 billion rupees.
The rupee ended firmer at 126.25/35 to the dollar from Wednesday's close of 126.50/55 due to exporter dollar conversions, dealers said. ($1 = 126.4500 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Sanjeev Miglani)
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