Are US stocks really over-valued?

Let us start with Warren Buffet’s favorite market valuation ratio: stock market capitalization to GDP. I have modified this slightly, replacing GDP with GNP, because the former excludes offshore earnings — a significant factor for multinationals.

US stock market capitalization to GNP

The ratio of stock market capitalization to GNP now exceeds the highs of 2005/2006, suggesting that stocks are over-valued — approaching the heady days of the Dotcom era.

Corporate Profits

If we dig a bit deeper, however, while the ratio of market cap to sales is also high, market cap to corporate profits remains low.

US stock market capitalization to Business Sales and Corporate Profits

Clearly profit margins have widened, with corporate profits increasing at a faster rate than sales. The critical question: is this sustainable?

Sustainability of Profits

At some point profit margins must narrow in response to rising costs. Increases in aggregate demand may lift employment and sales, but also drive up labor costs.

Profits and Labor Costs as a percentage of Net Value Added

The brown line above depicts labor costs as a percentage of net value added, compared to corporate profits (blue) as a percentage of net value added. There is a clear inverse relationship: when labor costs rise, profit margins fall (and vice versa). At first the effect of narrower margins is masked by rising sales, but eventually aggregate profits contract when sales growth slows (gray stripes indicate past recessions).

Interest Rates and Taxes

Other contributing factors to high corporate profits are interest rates and taxes. Corporate profits (% of GNP) have soared over the last 30 years as bond yields have fallen. The benefit is two-fold, with lower interest rates reducing the cost of corporate debt and lower finance costs boosting sales of consumer durables.

Corporate Profits as % of GNP and AAA Bond Yields

Lower effective corporate tax rates (gray) have also contributed to the surge in profits as a percentage of GNP.

US stock market capitalization to GNP

The most enduring of these three factors (labor costs, interest rates, and tax rates) is likely to be taxes. Corporate tax rates have fallen in most jurisdictions and US rates are high by comparison. Even if a long-overdue overhaul of corporate taxation is achieved in the next decade (don’t hold your breath), the overall tax rate is likely to remain low.

If Not Now, When?

The other two factors (labor costs and interest rates) may not be sustainable in the long-term but it will take time for them to normalize.

Treasury yields are rising, with the 10-year at 2.37 percent. Breakout above 3.0 percent still appears some way off, but would confirm the end of the 35-year secular down-trend.

10-Year Treasury Yields Secular Trend

Interest rates are likely to remain low until rising labor costs force the Fed to adopt a restrictive stance.

Labor Costs as a percentage of Net Value Added

Labor markets have tightened to some extent, as indicated by the higher trough on the right of the above graph. But this is likely to be slowed by the low participation rate, with potential employees returning to the workforce, and a strong dollar enhancing the attraction of cheap labor in emerging markets.

Hourly earnings growth in the manufacturing sector remains comfortably below the Fed’s 2.0 percent inflation target. Any breakout above this level, however, would be cause for concern. Not only would the Fed be likely to raise interest rates, but profit margins are likely to shrink.

Manufacturing: Hourly Earnings Growth

For the present

None of the macroeconomic and volatility filters that we monitor indicate elevated market risk. I expect them to rise over the next two to three years as the labor market tightens and interest rates increase, but for the present we maintain full exposure to equities.