50 in spot trade to 120.00/10 by mid-day, brokers and dealers said.
The All Share Price Index of the Colombo stock gained 0.46 percent (8.36 points) to end at 1,834.75 while the Milanka index of liquid stocks was up 0.
51 percent (9.93 points) to close at 1,961.21, according to provisional stock exchange data.
Turnover was 80.8 million rupees.
"The market expects institutional participation to improve with interest rates coming down," said Shivantha Meepage of Acuity Stockbrokers.
"The medium term outlook is good for the market with interest rates coming down," said Meepage.
"However profit taking will occur at regular intervals."
Index heavy fixed line telecom provider Sri Lanka Telecom gained 25 cents to close at 38.75, while mobile giant Dialog closed flat at 5.
25 rupees.
Sampatha Bank gained 2.50 rupees to close at 76.50.
Conglomerate JKH gained 25 cents to close at 72.
00.
Sri Lanka's largest privately owned bank, Commercial Bank, lost 25 cents to close at 88.75, while the diversified Hayleys lost 50 cents to close at 103.
00 rupees, on thin volumes.