Prudential Securities said it has acquired Volpe Brown Whelan & Co., among one of the few remaining independent investment banks, as it seeks a piece of the lucrative business of helping technology companies sell stock to the public. Terms of the cash transaction were not disclosed. Prudential, the brokerage arm of Prudential Insurance Co. of America, said the new unit will be called Prudential Volpe Technology Group, will incorporate Prudential's existing technology banking group, and will be based in San Francisco. It will be managed by Thomas Volpe and Robert Whelan. Volpe Brown has about 220 employees in its offices in San Francisco, Boston and Seattle. For the acquired company, the deal will allow it to expand its ability to distribute stock offerings. It also will become a contender to lead in stock underwriting transactions, Thomas Volpe said. Since 1992, Volpe Brown has been lead or co-manager on more than 220 public offerings worth a total of more than $12 billion. About 90% of its business now comes from the technology sector, Volpe said. Prudential's expansion in this area follows Chase Manhattan Corp.'s acquisition of West Coast investment bank Hambrecht & Quist earlier this month.