Invisible Stock Bubble; Russell Napier sees S&P 500 Drop to 400

``History suggests today's corporate earnings are unsustainably high relative to the size of the economy. The real price-to-earnings ratio, based on a more normal level of earnings, is well over 20... Last year corporate profits reached 9.4 cents per dollar of national income. That's 47% too high by historic standards. If earnings were to shrink to their historic average, the aforementioned P-E ratio of 15.3 for the broad stock market would rise to nearly 23. The result would almost surely be a plunge in share prices.''