The All Share Price Index lost 30.55 points to end at 1,968.29 while the Milanka shed 1.14 percent (25.49 points) to close at 2,210.45. Turnover was 213 million rupees.
Brokers said trading volumes were slightly higher than last week, possibly because investors may be thinking that prices had fallen to attractive levels.
"There's some fear that foreign selling might come in," said Sujeeva Pieris of Bartleet Mallory Stockbrokers.
"When other markets have come down drastically, investors might tend to take their money out whenever possible and invest in those markets which are cheap.
"
But he also noted a lack of buying support.
The main contributor to the day's trading volume was Dialog Telekom with 3,261,000 shares done mostly between 7.
75 and eight rupees and a block of 3.
1 million shares changing hands at eight rupees.
Another heavyweight, John Keells Holdings, was the most actively traded stock and most active in terms of volumes, falling 3.79 percent (2.75 rupees) to end at 69.75 with 799,000 shares traded.
There was also a large transaction in Chevron Lubricants Lanka, formerly Caltex, with a foreign investor selling 670,000 shares at 110 rupees to a local buyer.
The stock had closed previously at 106 rupees.
Chevron Lubricants Lanka Friday announced its third interim dividend of 2.
50 rupees per share.
The company, known for paying good dividends, said net profit for the September quarter had fallen and that it expects high base oil prices and lower sales to affect margins and earnings in the next quarter as well.
Carson Cumberbatch fell 3.68 percent (seven rupees) to 183 rupees.
The group has stakes in east Asian plantations growing palm oil whose price has fallen steeply in recent weeks, leading to fears among investors that the firm's earnings would be hit in the coming quarters.
"The main contributor to revenue is palm oil," said Pieris. "When oil prices fall, there's a tendency for palm oil to fall.
"But it’s a well diversified firm, so the impact would not be that much, as it was making good profits even when palm oil prices were much lower."
Malwatte Valley Plantations, not a very liquid stock, was the biggest loser of the day, plunging 22.50 percent or nine rupees to 31 rupees with 91,000 shares changing hands.
Brokers said investors may be worried about falling prices of tea, which have come down in line with the drop in commodity prices.
Furthermore, the Uva season, when teas from Malwatte Valley, fetch their best prices, has come to an end.
"There's been an overall fall in commodity prices.
Also, plantations went up rapidly in the first half of the year," said Pieris.
"So there might still be investors who can afford to sell at a profit and may be exiting knowing that tea and rubber prices are coming down, which may affect company earnings."
Corrected - reference to Chevron dividend announcement