Worst Quarter in Five Years?

"These are the sectors and the companies that have held up the best throughout the credit crisis, and they've attracted lots of attention," Pavlik says. "I'd like to see them deliver, but it does make me a little nervous because they've had quite a run recently."

Thomson Financial, though, projects that the best performing sector of the third quarter will be health care, expected to have a 12% expansion rate. Merck (MRK Quote), UnitedHealth (UNH Quote), Amgen (AMGN Quote) and Bristol-Myers Squibb (BMY Quote) are all due to report over the next two weeks.

Analysts also hope that guidance out of technology, industrials and even materials names will help support a year-end rally despite concerns about the effects of a weaker dollar and inflationary pressures. As usual, projections for the fourth quarter could have more of an impact than third-quarter earnings surprises.

"Conceptually, changing trends seem more likely to show up in guidance than in actual earnings," says McCain. "We expect earnings surprises to be modest but positive, with the major news coming again from guidance about the future."