The S&P SL20 closed 1.14 lower at 3,260.62, down 0.03 percent, after reaching an intraday high of 3,269.39.
Turnover was 528.71 million rupees, up from 372.54 million a day earlier, with stocks of 98 firms closing in the red against 78 gainers.
Nestle Lanka closed 39.20 rupees lower at 1,910.80 rupees and Colombo Leasing and Finance closed 30 cents lower at 3.90 rupees.
Cargills Ceylon closed 7.90 rupees lower at 148.10 rupees and Sri Lanka Telecom closed 70 cents lower at 39.10 rupees.
Distilleries closed 3.80 rupees lower at 185.00 rupees.
JKH closed 1.80 rupees higher at 219.90 rupees and Com Bank closed 1.10 rupees higher at 117.70 rupees and featured in a single crossing.
Bukit Darah closed 7.30 rupees higher at 683.00 rupees and Ceylinco Insurance closed 23.90 rupees higher at 1,300.00 rupees.
Textured Jersey closed 50 cents higher at 15.80 rupees.
Speculative trading continued in troubled Touchwood, up 10 cents to 3.90 rupees, with more than 1.4 million shares changing hands.
PCH Holdings closed 20 cents higher at 1.70 rupees with more than 14.78 million shares traded. PC House closed 10 cents lower at 80 cents with more than 1.3 million shares traded.
Free Lanka closed 10 cents higher at 2.50 rupees with more than 10.7 million shares traded.
NDB Bank closed 10 cents at 158.00 rupees and Union Bank closed 50 cents higher at 17.80 rupees.
The rupee was quoted weaker at 131.05/10 against the US dollar in late trading in the spot market due to importer demand, currency dealers said. The rupee opened at 130.95/131.00 against the US dollar. The Central Bank was seen intervening to keep the rupee steady at 131.10.
The Central Bank has bought hundreds of millions of dollars generating large volumes of rupee liquidity.
Excess rupee liquidity is now about 35 billion rupees pointing around 300 million dollars of unsterilized purchases.
Unless they are followed up with unsterilized dollar sales, the rupee's loose peg to the dollar weakens.
A more liquid five year Treasury bond was trading at 10.75/80 percent after opening at 10.72/84 percent amidst heavy trading.