RAINIER <RBAN> COMPLETES ACQUISITION Rainier Bancorp said it completed the acquisition of Tacoma, Wash.-based United Bank, for 59 mln dlrs worth of Rainier stock. United, a savings bank with 607 mln dlrs in assets and 23 offices, will operate as a wholly-owned subsidiary, Rainier said. Rainier, which last month agreed to merge with Security Pacific Corp <SPC>, said the United acquisition will increase its assets to 9.8 billion dlrs from the 9.2 billion reported at the end of 1986.