Volume traded totalled 706 million shares worth 676 million Singapore dollars (398 million US), down from 1.06 billion shares worth 1.13 billion dollars on Friday.
There were 175 rising issues, 323 decliners and 631 issues were even.
"Last week it went up quite a lot despite the holiday-shortened week," said an analyst from a local brokerage. Financial markets in Singapore were closed Tuesday and Thursday last week for public holidays.
"Now that most of the market players are back from holiday maybe they are just selling into the recent strength of the market."
The market is likely to stay at current levels in the short-term with little new corporate developments expected, dealers said.
For the blue chips, Singapore Press Holdings was flat at 4.46, Singapore Airlines fell 10 cents to 11.40 and ST Engineering declined six cents to 2.56.
Singapore Telecommunications was two cents higher at 2.40 ahead of this week's release of its September quarter earnings results.
Banking stocks were flat to lower with DBS steady at 15.60, Oversea-Chinese Banking Corp down five cents to 6.25 and United Overseas Bank retreated 20 cents to 14.00.
In the technology sector, Creative Technology rose 10 cents to 12.60, Chartered Semiconductor was flat at 1.10 and Venture fell 20 cents to 13.00.
For the property sector, CapitaLand gained two cents to 3.38, City Developments slipped five cents to 8.70 and Keppel Land was unchanged at 3.98.