MANILA, Philippines (AP) -- Philippine shares plunged Friday, marking their biggest drop in 10 years in reaction to a sharp decline overnight on Wall Street. A technical problem that delayed the opening of the bourse by more than an hour added to the anxiety.

The 30-company Philippine Stock Exchange Index plummeted 140.92 points, or 3.9 percent, to 3,518.76 -- its steepest single day fall since August 28, 1997. The index rose 0.4 percent Thursday.

"Investor sentiment, already hurt by Wall Street, was aggravated by the (technical) glitch," said Rommel Macapagal, chairman of Westlink global Equities.

Trading was extended by an hour to make for the late opening.

"The root of the problem is the subprime mortgage worries in the U.S., so this might last until September. August is a weak month for Manila markets," said Jose Vistan at AB Capital Securities

Investors will closely watch U.S. equities later Friday to find trading leads for Monday.

Losers, led by property developer Vista Land & Lifescapes Inc., outnumbered gainers 141 to 8, with 24 issues unchanged. Vista Land, which listed shares sold in a follow-on offer on Thursday, fell 5.8 percent to 6.50 pesos.

Philippine Long Distance Telephone Co., whose American depositary receipts fell 2 percent overnight in New York, retreated 1.3 percent to 2,625 pesos.

April Tan, research head at CitisecOnline.Com, said that Manila stocks' fundamentals remain strong but the shares were technically overbought following the market's recent rise to a new record high.