Virgin, Alaska and JetBlue compete in a tier below the giants that are American, Delta and United. When Virgin put itself up for sale this year, it drew preliminary interest from a host of potential suitors. But the biggest domestic airlines, constrained by antitrust regulations, soon gave way to smaller competitors eager to expand their networks.

Alaska and JetBlue squared off in the final round of bidding, with official offers coming in recent days. But Alaska, one of the rare airlines to hold an investment-grade credit rating and one with more cash on its books than some others, appears to have triumphed.

During the contest, Alaska also argued that it would need to divest fewer airport slots than JetBlue would, since its network has fewer overlaps with Virgin’s, according to the person briefed on the matter.

Any transaction will probably draw close scrutiny from government regulators, who have become more suspicious of airline mergers because of the potential for them to result in higher prices. The Justice Department went to court to challenge American’s takeover of US Airways, though it lost that legal fight.

A sale of Virgin would mean a quick end to independence for an airline that began flying more than a decade ago. The company was the brainchild of Richard Branson, the outspoken billionaire behind the Virgin empire of brands.