The main stock index edged up 0.23 percent, or 14.53 points, to close at 6,221.12.
Foreign investors bought net 859.9 million rupees of shares, the highest since March 7, extending net foreign inflows this year to 10.76 billion rupees.
'Interest in blue chips pushed the market up, while large caps dominated the turnover,' a stockbroker said on condition of anonymity.
Shares in John Keells Holdings rose 0.44 percent to 274.20 rupees per share, their all-time high.
The central bank on Friday cut key policy rates by 50 basis point, following some of its regional peers, to boost economic growth amid subdued demand. The cuts were expected ever since Treasury Secretary P.B. Jayasundera said on April 9 that interest rates could ease in May or June.
Market turnover was 1.7 billion rupees ($13.47 million) on Wednesday, more than this year's daily average of 1.03 billion rupees.
The rupee ended firmer at 125.90/126.10 from Tuesday's close of 126.50/55 on exporter dollar sales, currency dealers said. ($1 = 126.2500 Sri Lanka rupees)
(Reporting by Ranga Sirilal and Shihar Aneez; Editing by Prateek Chatterjee)
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