United Airlines as a whole is losing money and was bleeding cash. The frequent flyer program unit -- MileagePlus -- was taking in cash faster than it was spending it and was a profit center when looked at as a standalone unit. I hope that helps explain it a bit.

Also, a business unit can be worth more than its parent. And when the parent company or parent company's other main units are generating losses and drawing down the cash while one subsidiary is not, a break-up could show that one subsidiary is worth more than the (former) whole -- since the value of the loss-making business units (as one entity) can be far lower than that of a profit-making business unit by itself.