The main share index fell 0.64 percent, or 37.11 points, to end at 5,737.48, its lowest since January 10.
Shares of Dialog Axiata fell 2.2 percent to 9.90 rupees. On Monday it reported a 30 percent fall in its December quarter profit.
The day's turnover was 1.52 billion rupees ($11.99 million), higher than this year's daily average of 1.12 billion rupees.
Foreign investors were net buyers of 301.1 million rupees worth of shares on Tuesday, but they have been net sellers of 614.6 million rupees so far this year.
The rupee ended weaker at 127.20/30 to the dollar, its lowest since January 1, from Monday's close of 126.90/95 due to importer dollar demand, dealers said.
($1 = 126.8000 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Sanjeev Miglani)