The main share index edged down 0.19 percent, or 10.85 points, to close at 5,783.62.
Foreign investors were net buyers of 111.9 million rupees ($846,600) worth of shares on Wednesday, extending net foreign inflows in equities this year to 19.49 billion rupees.
Shares in George Steuart Finance Ltd fell 20 percent to 488 rupees while Ceylon Tobacco Company PLC fell 0.6 percent to 1041.00 rupees.
Shares in top conglomerate John Keells Holdings rose 0.9 percent to 222.90 rupees on foreign buying.
Wednesday's turnover was 582.8 million rupees, well below this year's daily average of about 877.5 million rupees.
($1=132.1750 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Clarence Fernandez)
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