The All Share Price Index fell 0.19 percent (4.72 points) to end at 2,480.56 while the more liquid Milanka fell 0.37 percent (10.21 points) to close at 2,763.42, according to provisional stock exchange figures.
Turnover was 558 million rupees.
Chinthana Hatangala of Lanka Securities said both retail and institutional investors took part in trading, with the indices fluctuating during the day.
"Lanka Cement and Overseas Realty were activley traded throughout the day," he said.
"We also saw some relative improvement in interest for banking sector shares."
Lanka Cement closed at 38.75 rupees a share, up two rupees or 5.
44 percent, according to the volume weighted average price, with almost 2.
3 million shares traded.
The stock has seen bouts of heavy trading from time to time owing to foreign interest in reviving a defunct cement plant sitting on a rich deposit of limestone in northen Jaffna.
With the end of the island's ethnic war, construction activity is expected to pick up, especially in rebuilding in the north and east, along with the property market.
Overseas Realty closed at 14.75, up 0.25 cents with over 2.5 million shares changing hands.
Foreign activity was low with buying of 76.9 million rupees worth shares and selling of 76.03 million. Foreign participation was only 13.7 percent of total market activity.
The highest contributor to turnover came from trading in Commercial Bank, Lanka Cement and Ceylinco Insurance, with banking sector shares also going up, especally Commercial Bank, DFCC and Hatton National Bank.
There were two crossings or off-the-floor negotiated deals, of Commercial Bank shares with one deal of 100,000 shares going at 142 rupees and a smaller one at 140 rupees.
There were also two crossings of Ceylinco Insurance, one of 150,000 shares at 200 rupees and two deals of 50,000 shares each at 200.
About 2.14 million shares of Dialog Telekom were traded at 5.25 and a crossing of DFCC of 74,600 shares at 138.