The island nation's main share index closed 0.92 or 56.81 points down at 6,087.86 from its highest since Nov. 14. On Thursday, SEC Chairperson Indrani Sugathadasa stepped down "to uphold her principles," barely a month after her deputy
was moved amid broker complaints that tougher regulation was hurting sentiment.
"Though the market is driven on the sentiment that there will be more credits and margin trading, those will not boost share prices fundamentally," said an analyst on condition of anonymity.
Brokers have complained investor sentiment has turned negative due to firmer regulation by the SEC, which has looked into price manipulation and cut the amount of credit available, which has hit broker commissions and trading volume.
The bourse surged 4.14 percent on Monday from a 14-month low after Rajapaksa met the heads of stock brokerages who urged the president to take action to help the bourse rebound.
The day's turnover was 1.44 billion Sri Lanka rupees ($12.65 million), less than last year's average of 2.4 billion and this year's 2.4 billion.
Shares in retail favourite Touchwood Investment PLC fell 3.43 percent to 22.50 rupees while Entrust Securities Ltd fell 0.28 percent to 70.70 rupees.
Market heavyweight John Keells Holdings PLC, which saw foreign selling of 114,100 shares, ended 1.00 percent weaker at 168.20 rupees.
Total volume was 83.7 million shares, against a five-day average of 90.6 million. The 30-day and 90-day average trading volumes were 61.2 million and 102.7 million. Last year's daily average was 67.9 million.
The bourse has fallen 10.26 percent since Oct. 1. It is now Asia's 12th-best performer with a year-to-date loss of 8.26 percent after being at the top until June. It gave Asia's best returns in 2009 and 2010.
The bourse saw a net foreign outflow of 49.5 million rupees on Friday, and thus far in 2011, offshore investors have sold 17.8 billion, and a record 26.4 billion in 2010.
On Friday, the bourse was in neutral territory with the 14-day relative strength index at 44.2, above the lower neutral range of 30. Gainers outnumbered losers by 159 to 44 on Friday, Thomson Reuters data showed.
The rupee closed flat at 113.89/90 rupees a dollar for the eighth straight session, dealers said.
The central bank on Friday sold around $10 million to defend the currency, dealers said, extending its total dollar sales to $220 million since the 3 percent devaluation on Nov. 22.