A good measure of market participation -- the number of stocks participating in upside price moves -- is the percentage of stocks above their 200-day moving average. DecisionPoint.com tracks this number on the major market indexes, and in this instance we are looking at this indicator for the S&P 600 Small-Cap Index.
Note how the indicator has been making lower highs for the last 18 months, even as the price index has made new all-time highs. This negative divergence is not necessarily fatal, but it does reflect how the price index is being supported by fewer and fewer stocks.
The price index can move higher because it is capitalization-weighted. This allows the larger-cap stocks in the index to carry it higher, while increasing numbers of smaller-cap stocks begin to fade. This is not healthy, and it is another piece of evidence that indicates that the cyclical bull market is probably near an end.