The industrial giant's sluggish U.S. results -- and downbeat outlook -- cast a pall over prospects for corporate profits and the economy

Though its global business is booming, Caterpillar (CAT) sounded the alarm Oct. 19 about the U.S. economy, warning an already lousy situation at home shows no end in sight.

The heavy equipment powerhouse's earnings report ended one of the worst weeks for corporate earnings in five years.

Disappointments from Citigroup (C) and Bank of America (BAC) grabbed headlines, but "it's been pretty brutal across the board," says Ashwani Kaul, an analyst who watches earnings expectations for Reuters Estimates.

At the beginning of the week, Reuters Estimates