Turnover was 1.2 billion rupees.
Commercial Bank of Ceylon closed at 104.10 rupees down 10 cents with a 5.1 million share off-market deal also contributing. The stock contributed 631 million rupees to turnover.
Environmental Resources Holdings saw 5.3 million shares traded at 19.10 rupees up 90 cents.
Carsons Cumberbatch closed at 449.80 up 5.80 rupees contributing most to the index followed by LOLC which closed at 71.50 up 1.50 cents.
Dialog Axiata closed at 8.50 down 10 cents.
In forex markets the rupee weakened as much as 127.10/15 in late trading Wednesday donw from Tuesday's close of around 126.75/85 rupees.
Liquidity has surged in Sri Lanka's forex markets putting pressure on the dollar peg. Excess liquidity rose to 41 billion rupees on January 22.
Analysts say the Central Bank could kill some liquidity by selling down its reserves (unsterilized sales) to prevent the rupee weakening.