The $2.3 billion merger between Pennsylvania-based Rite Aid Corp. and Oregon-based Thrifty PayLess Holdings Inc. has been completed following a vote of shareholder approval by both drugstore chains.

The acquisition, announced in mid-October, created a chain of more than 3,500 drugstores with annual revenues of slightly more than $10 billion, just behind Walgreen Co., the nation’s largest drug retailer based on annual sales.

Rite Aid immediately announced it will lay off a group of Thrifty PayLess officers and senior executives today and will give 60-day layoff notices to about 700 other headquarters employees in Wilsonville.