Excerpt: Rising pension costs threaten to eat into the profits of many of the Chicago area's largest companies as they divert billions of dollars to shore up funds depleted by the stock market swoon. Aon Corp., Exelon Corp., Abbott Laboratories, Caterpillar Inc., Motorola Inc. and Sara Lee Corp. are among the region's companies that started the year without enough in their pension funds to cover projected payments to retirees. Those shortfalls almost certainly have deepened, observers say.

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