When you need only one handful of fingers to count which stocks are responsible for all the points needed to account for the rally, that’s just one half of the conditions to look like the bubble days. The other half is a lack of participation of most other stocks. Sifting the data since 1996, the majority of other sessions where the S&P rose 0.28% or more but 42% or fewer of the stocks in the index gained can be found in 1999 and 2000. One day does not a bubble make, however. As the table makes clear, the Internet bubble was many months in the making with the most egregious string of narrow rallies clustered around the peak in late 1999 and early 2000. We’re nowhere near that now. would be nice to see a record high on broad participation and rising trading volume. S&P 500 trading is nearly 30% below the 20-day average. And that’s enough to engender concern that this latest leg higher is going to buckle once trading desks are fully staffed in the not-too-distant future.