They said the market consolidated in the absence of fresh positive leads and amid mounting concerns over a political scandal linking President Arroyos husband and a son to gambling activities.
The charges, made by the political opposition, have not been substantiated and already denied by the President.
The Philippine Stock Exchange composite index shed 3.25 points to 1,883.48. It traded between 1,878.25 and 1,886.73.
The broader all-shares index retreated 1.85 points to 1,150.98.
Losers and gainers were equal at 30 each, while 43 stocks ended unchanged.
Philippine Long Distance Telephone Co. (PLDT) was the most active stock. It ended down P10 at P1,455, tracking Fridays fall of its American Depositary Receipts.
"Investors are largely watching on the sidelines and have preferred to hold onto their shares for the meantime. They want to know how this political controversy would unfold," said Jose Vistan of AB Capital Securities.
He was referring to an upcoming investigation by the Senate on allegations that presidential spouse Jose Miguel Arroyo and son Juan Miguel were taking bribes from operators of a popular illegal numbers game called "jueteng."
Similar allegations had led to the impeachment and subsequent ouster of president Joseph Estrada in 2001.
Nina Tinio, an analyst at Unicapital Securities Inc., said the recent weakness of the peso against the dollar may have also dampened trade as this reduces investors trading gains.
The local unit hit an intra-day low of 54.735 to the dollar in morning trade, its weakest level in nearly five weeks, after closing at 54.575 on Friday.
"The participation of foreign investors in the domestic market in the past two months has been on a decline, and that has led to a sharp drop in our markets low value turnover," Tinio added.
Semirara Mining Corp. was the second most briskly traded counter, down 50 centavos at P28.50 .
Ayala Corp. fell 10 centavos to P6.80, while unit Ayala Land gained 10 centavos to P7.30.
San Miguel Corp. B, available to foreign investors, was down 50 centavos at P85. San Miguel A, limited to locals, was unchanged at P58.50.
Manila Electric B, declined 25 centavos to P23.50 while Manila Electric A gave up 50 centavos at P15.75.
An investment conference Monday did little to lift market sentiment despite the governments efforts to push infrastructure spending in the country, traders said. AFP, AP