New Highs In The A-D Line and the Small Cap Index Are Not Necessarily Bullish
Summary: The conventional wisdom is that "healthy breadth" is necessarily bullish. This sounds intuitively correct: a broader foundation - where more stocks are ticking higher - should equal a more solid market, but it is empirically false. Equities can continue to move higher when breadth is healthy, but new highs in the advance-decline line or in the small cap index have also preceded drops of 10, 20 or even 50% in the equity market.
The conventional wisdom is that "healthy breadth" leads to higher equity prices. This sounds intuitively correct: a broader foundation - where more stocks are ticking higher - should equal a more solid market. Conversely, a narrowing market should be a warning of a likely market top.
But it is empirically false. Consider some recent research into this issue.
The Russell small cap index (RUT) has been making new highs even as the large cap indices have not. Because there are four times as many stocks in RUT as in SPX, many infer that breadth is broadening and that this must be bullish for all equities. "When the troops lead, the generals will follow."
Yet, as Mark Hulbert points out, small caps have peaked after the major stock indices in more than half of the 29 bull markets since 1926. If the conventional wisdom was correct, small caps should lead by peaking before the major indices, but this happened only a third of the time (Mark's article is here).
Similarly, Rob Hanna notes that when small caps make a new high before the major indices, the odds of the SPX moving higher are no better than random. There is no edge (Rob's article is here).