In agreeing to buy Virgin America for $2.6 billion, Alaska Air Group is betting that the airline industry is so consolidated after years of mergers that what it needs is another takeover.

The acquisition of Virgin America, the sleek but embattled young airline that sought to make flying across the United States stylish, would propel Alaska Airlines into the top five American carriers. The deal, announced on Monday, would also prove especially helpful in giving the older airline valuable space at major California airports and lucrative transcontinental routes.

At the same time, Alaska Air must now be careful in how it integrates a brand beloved by its cadre of customers who adore its cheeky image, onboard Wi-Fi and soothing onboard purple lighting.

For Alaska Air, buying Virgin America was in some ways a natural consequence of the successive mergers that have already concentrated domestic air travel in four primary airlines: American, Delta, United and Southwest. Together, they control roughly 85 percent of the country’s airline capacity.