Pilipinas Shell Petroleum Corp. has filed for an IPO of shares that could raise as much as 29.7 billion pesos (US$629 million) in one of the Philippines' largest stock market listings.

The unit of Royal Dutch Shell Plc (NYSE: RDS.A) plans to launch the IPO in October involving up to 330 million primary and secondary shares at up to 90 pesos per share, with a listing on the Philippine Stock Exchange tentatively set for Nov. 10.

If approved by regulators, it could be the country's third IPO this year, and could be bigger than the recent $532 million maiden share sale by cement maker Cemex Holdings Philippines Inc., which was the country's largest listing in three years.

The offer size will represent an 18.6% share of Pilipinas Shell after the IPO, a regulatory filing on July 26 showed.

The Pilipinas Shell IPO comes as the local bourse is showing signs of stability after months of volatility that prompted companies such as Datem Inc. and D.M. Wenceslao & Associates Inc. to defer their listings.

Manila's benchmark stock index soared to a 15-month high last week, with investor confidence getting a boost from expectations that the Philippine economy will continue to outperform some of its Asian neighbors.

"The Philippines is an outlier because economic prospects for our country remain favorable," Noel Reyes, chief investment officer of Security Bank Corp., told Reuters. "We are going to be the safe haven for Asia, given that the growth track for other Asian economies is weak."

The IPO is being handled by BPI Capital Corp. and JP Morgan. Proceeds will be used to fund capex, working capital and general corporate expenses.

Pilipinas Shell, which operates one of the country's two oil refineries, is required under a two-decades-old law to offer at least 10% of its equity to the public. But listing plans had to be deferred several times, with the company citing unfavorable market conditions and the need for refinery upgrades.