20 companies that lost the most

AMR Corporation, parent of American Airlines, resisted bankruptcy for years. But in 2011, high fuel costs, economic uncertainty, and a flagging economy compelled the company to file for Chapter 11 in November. It was the last of the so-called "legacy airlines" -- the five carriers that existed pre-deregulation -- to take the plunge.

The move signals the beginning of what's likely to be a major reorganization. Union contracts will be renegotiated, marginal routes will be dropped, and a merger could be on the horizon. AMR's smaller rival US Airways has emerged as an aggressive suitor. In April it secured an agreement from the company's three major unions in support of a possible merger. The merger, unions claim, could save some 3,500 jobs from the bankruptcy chopping block.

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