Nervousness heading into earnings season

Wall Street heads into earnings season this week playing a typical game: worrying about results a lot, and then rallying on pleasant surprises.

Analysts have been lowering earnings estimates of late and nervousness about the U.S. economic picture abounds, especially after Friday's poor June jobs report.

However, profit growth could still be strong in the second quarter -- and that could boost stocks. The Standard & Poor's 500 fell 0.4 percent in the second quarter, but rallied in recent days on hopes for economic improvement.

Over the last month, analysts have revised downward earnings estimates for S&P 500 companies, with the mean change in earnings estimates a negative 6.4 percent, according to Thomson Reuters StarMine data.

"I think there's going to be a lot of anxiety going into it, and I think companies are going to continue what they've done for the last few quarters: Put out better-than-expected numbers, and guidance should be OK," said Scott Billeaudeau, portfolio manager at Fifth Third Asset Management, in Minneapolis.

S&P 500 components' earnings are expected to have increased an average of 7.3 percent in the second quarter from a year ago, down from first-quarter growth of 18.9 percent, Thomson Reuters data showed.