The ratio of sales to assets is an asset turnover ratio that measures the sales-generating capacity of a given asset base. Taking the nominal GDP of the nonfinancial corporate sector as a measure for sales. The ratio has started to turn up at the beginning of 2001. This pattern is normally consistent with periods of recovery. However, it should be noted that this ratio is near its historical low. The z-score for the nonfinancial corporate sector has collapsed dramatically since 2000, resting well below the critical level of 1.8 since the second quarter of 2002. For an individual firm this signals that the company is likely to fail within 2 years. On the macro level it indicates a high probability of rising default rates and widening credit spreads. Three points stand out:

• based on macroeconomic data the z-score has never been in the safe zone;
• the average score since 1952 is about 2;
• in the 1970s and 1980s, the z-score was permanently in the distress zone implying that corporate America should have gone bankrupt, but clearly it survived.

This leads to the conclusion that the weighting scheme is no longer appropriate to capture the vulnerability of the corporate sector. The relative importance of the individual factors changes over time. Therefore, it is necessary to adjust the weighting scheme on a regular basis, for example by using a regression methodology.