As share prices fall, margins decline and revenues may fail to cover fixed costs.

ECONOMIST: Fund management

It became much more difficult to cover fixed costs or acquire inventory using a volume discount, so the result was a decrease in profitability.

FORBES: When Will Hiring Pick Up

First, traditional retailers may need to think about closing more stores in 2012 as the least-trafficked outlets fail to generate enough sales to cover fixed overhead costs.

FORBES: Avoid Amazon -- Buy These Cheaper Stocks Instead