Most companies guiding lower in at least 7 years

As Wall Street deals with the effects of the U.S. government shutdown, investors are also bracing for another hectic earnings season set to begin this month.

Preliminary guidance for third-quarter results provides little case for optimism. For Q3 2013, only 18 companies have issued positive EPS guidance, whereas 94 companies have issued negative guidance—the highest number since at least 2006, according to figures compiled by Thomson Reuters I/B/E/S.

These numbers produce a negative-to-positive ratio of over 5, which is higher than the 15-year average.

Within the S&P 500, the Technology sector (27) has the highest number of companies issuing negative guidance, followed by Consumer Discretionary (18) and Industrial (13) stocks.

For some of these names, the sharpness of the decrease has been significant. Consider Abercrombie & Fitch, for example. Analysts expected EPS figures to come in at around $1.063 per share, whereas the company gave a guidance of 42.5 cents, a drop of roughly 60 percent.

Similarly, the expectation for Tenet Healthcare stood at 68.2 cents per share, compared with the company's guidance of 42.5 cents—38 percent lower than expected.

Should investors be concerned?

So far this quarter, 21 S&P 500 companies reported Q3 2013 EPS. Of those names, 13 beat analysts estimates, four missed and four met expectations. The blended EPS growth estimate is 4.5 percent, while the revenue growth estimate is 3 percent.

Here's a look at some of the S&P companies providing negative guidance for Q3: