They said although Wall Street and the Japanese market reacted calmly to North Koreas first-ever nuclear test, investors remained wary over the geopolitical tensions which could follow.
The composite index fell 22.94 points to 2,528.98 after trading between 2,518.87 and 2,548.74.
The broader all-share index fell 11.31 points to 1,555.94.
Losers led gainers 43 to 40, with 56 stocks unchanged.
Volume was 734.98 million shares worth P2.293 billion.
"Investors took a cautious stance and the market is also undergoing a correction which we expect to continue in the next few days," said Harry Liu, of Summit Securities.
Liu said the tensions arising from North Koreas nuclear weapons test also weighed on market sentiment but it was more of a knee-jerk reaction.
"The market is more concerned about seeking a support level that will encourage investors to come in again," noted Liu.
The long-term outlook is bright given the Philippines firm economic fundamentals, said Lawrence de Leon of Accord Capital Equities.
"The market is still very bullish and is merely looking for a more comfortable level at which to start buying again," he said.
Top-traded Philippine Long Distance Telephone Co. (PLDT) was down P10 at P2,190.
Conglomerate Ayala Corp. fell P10 to P482.50 while unit Globe Telecom Inc. was down P50 at P1,095.
Food and beverage firm San Miguel Corp.s A-shares were steady at P65.50 while its B-shares fell 50 centavos to P76.
The Bureau of Customs (BoC), which contributes 20 percent of the governments annual income, missed its revenue goal for the first time in five months in September, Customs Commissioner Napoleon Morales said.
Customs revenue has helped the government offset a shortfall in collections by internal revenue, which delivers 70 percent of the governments annual income.
Higher tariffs and taxes allowed President Arroyos government to post a fourth monthly budget surplus in August, narrowing the budget deficit in the first eight months of the year to P34.2 billion or less than a third of the forecast.
"News about the customs bureau missing its target disappointed investors," said Astro del Castillo, managing director of First Grade Holding Inc., a financial management and advisory company in Manila. "Its made investors step on the brakes and see if the government can indeed sustain revenue collection to eventually meet its deficit target." AFP