One of the things we want to look at when the market pulls back from highs or bounces higher from lows is the degree of participation generated by the countertrend move.
Here we see one-minute NYSE TICK values for the day thus far, with the zero line highlighted with the purple horizontal line.
Note the deterioration in new 20-day highs minus lows in the last two weeks (pink line above), even as the S&P 500 Index (blue line) has been making bull market highs.
Each morning before the market open, I post 20-day new highs and lows via Twitter. For a broader market look, I like to examine the 65-day highs and lows. Above we see the new highs minus the new lows plotted against the S&P 500 Index (SPY; blue line).