32 percent (15.39 points) to close at 4,746.98.
Turnover was almost 1.35 billion rupees, according to stock exchange provisional figures.
"The indices seem to have hit a plateau as some shares which were seemingly overbought by investors seem to be losing steam," Nikita Tissera, research manager at stock brokering house SC Securities said.
"However, we remain positive on the March quarter earnings.
So far the earnings did not disappoint.
"Companies like Chevron, Dialog and Sampath Bank showed that bottom lines could be improved on flat revenues by paying more attention to prudent cost management."
Brokers said over 9.28 million shares of Dialog Telekom were traded, Monday. It closed at 8.50 rupees, up 25 cents, while Sri Lanka Telecom, Sri Lanka's largest fixed line operator closed at 37.
25 rupees, down 25 cents.
Sri Lanka's Dialog Telekom group made a profit of 705 million rupees in the March 2010 quarter from its core celco operations, after a loss of 1.86 billion a year ago.
Commercial Bank closed at 242.00 rupees, up 50 cents, Hatton National Bank closed at 234.
00 rupees, down 1.25, Sampath Bank closed at 282.25 rupees, up 4.00 and Seylan Bank closed at 58.75 rupees, up 25 cents.
Conglomerates Aitken Spence closed flat at 1,450.00 rupees, Hayleys closed at 280.25 rupees, up 25 cents, Hemas Holdings closed at 136.
00 rupees, up 2.25 and John Keells Holdings closed at 185.00 rupees, down 3.25.
JKH is the largest listed company at the Colombo Stock Exchange and accounts for 8.5 percent of market capitalization.
Chevron Lubricants Lanka closed at 170.50 rupees, down 50 cents, and Colombo Dockyard closed at 286.
50 rupees, down 3.50.
Distilleries Company of Sri Lanka closed at 123.
75 rupees, down 1.25.