Samuelson has offered the dictum that the stock market is “micro efficient” but “macro inefficient.” That is, the efficient markets hypothesis works much better for individual stocks than it does for the aggregate stock market. In this article, we review a strand of evidence in recent literature that supports Samuelson's dictum and present one simple test, based on a regression and a simple scatter diagram, that vividly illustrates the truth in Samuelson's dictum for the U.S. stock market data since 1926.(JEL G14)