The benchmark All Share Index closed 0.76 percent lower (19.47 points) at 2,546.56 points while the Milanka Index of liquid stocks slid 0.74 percent (23.86 points) to 3,200.08 points, Colombo Stock Exchange (CSE) provisional data showed.
"The interest was mainly on SLT and Dialog Telekom.
Dialog was down 25 cents which brought (the index) down seven points," Naren Godamunne vice president of DFCC stockbrokers said.
Index heavy dialog telecom shed 25 cents during afternoon trade, but closed flat at 17.50 rupees.
The 18 million SLT shares changed hands, contributing over 712.
5 million rupees to the day's turnover of 1.26 billion rupees. Investors are expecting Malaysia's UT group to buy into the company by taking all or part of a 35.2 percent stake now held by Japan's NTT.
The SLT shared closed up 25 cents at 39.50 rupees. So far in March over 75 million SLT shares have been traded, CSE data show.
Illiquid Bukit Darah, a Colombo listed Malaysian oil palm firm, shed ten rupees at 1,315 following a deal of 200 shares, further dragging indices down, brokers said.
The company's market capitalization is over 13.1 billion rupees which is around 1.
58 percent of the total market capitalization.
"Across the board, others also were slightly down," Godamunne said.
Commercial Bank of Ceylon shed one rupee to close at 143.
00 while Hatton National Bank closed 50 cents lower at 124.25 rupees.
John Keells Holdings closed 25 cents lower at 120.00 rupees.
Lanka Cement was up 25 cents at 16.00 rupees with over 657,000 shares changing hands.