earnings calendar

With more companies issuing warnings about their results in recent weeks, investors may see more than a few disappointments in the second-quarter earnings season.

Companies faced many sources of pressure on their bottom lines over the last quarter, including persistent unemployment, the disruption of the global supply chain from the Japanese earthquake and tsunami, and high commodity and energy costs.

"This is where we can get down to the fundamentals of this market and finally see how companies are actually doing in this economy," Jack Ablin, chief investment officer at Harris Private Bank, told CNN Money.

Once-lofty expectations for the second quarter have been slipping for weeks. The Standard & Poor's 500 share-weighted earnings estimate has dropped four weeks in a row, from $232.5 billion on June 9 to $222.9 billion last week.

Of greater concern is that 84 companies - 17% of the S&P 500 - have given negative preannouncements, while just 33 have given positive preannouncements, according to Thomson Reuters data.