The main share index edged up 0.01 percent, or 0.68 points, to end at 5,851.35, its highest since Jan. 28.
'We expect the bourse to slow as foreign investors will be away in the coming days due to Chinese new year,' a stockbroker said.
Sri Lanka's central bank will announce its interest rates for February on Tuesday and analysts expect the bank to keep them steady despite annual inflation running at a near-record high, a Reuters poll showed.
The day's turnover was 938 million rupees ($7.43 million), less than this year's daily average of 1.21 billion rupees.
Foreign investors were net sellers of 189.57 million rupees worth of shares on Monday, pushing up the net foreign outflow this year to 1.3 billion rupees.
The rupee ended weaker at 126.33/38 to the dollar from Friday's close of 126.20/30 as two state banks bought dollars to cover oil import bills, dealers said. ($1 = 126.3000 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Pravin Char)
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