I keep reading in forums and in the mainstream media that United Airlines “bought” Continental Airlines.

It’s not what happened at all.

United and Continental agreed to merge. A merger is a combination of two companies into a single enterprise.

A purchase is a purchase.

When United and Continental agreed to merge, they created a new corporation (UnitedContinental Holdings, Inc.) which issued new shares. These shares were traded for all of the outstanding and existing stock that each of United and Continental had. No United stock is left. No Continental stock is left.

Delta and Northwest recently combined. Delta, without changing its corporate structure, issued new shares and exchanged those for Northwest stock. Northwest, and all of its corporations ceased to exist entirely, and only Delta was the surviving entity.

That the trade name United is being used in the United Continental tie-up is the surviving name does not make it a purchase.