WASHINGTON: Alaska Airlines parent company Alaska Air Group said on Monday it was acquiring Virgin America in a friendly takeover worth around $4 billion. A definitive merger of the airlines had been unanimously approved by the boards of both companies, it said in a statement. Alaska Air will pay $57 in cash per share for Virgin America. “The combination expands Alaska Airlines’ existing footprint in California, bolsters its platform for growth and strengthens the company as a competitor to the four largest US airlines,” it said. The newly merged company will be headquartered in Seattle, it said.