Adv/Decl line

Worth watching intraday is the S&P500 Advance-Decline issues differential; whether it is positive or negative on the day and its interplay with the zero-line.
Just some snapshots here to show how it behaves, starting with today and going back to Monday:

Stayed positive most of the day and supported by the zero-line

Negative all day and extremely negative the later part of the day. When this extreme it works well to fade extreme NYSE TICK readings (around +800) for scalp trades.

Bullish breakout

 Interesting to see volume spikes that turn the market.  Here the A/D line showed a false breakout of the zero-line.

again, this is given even greater perspective using the NYSE TICK confirming with divergences or negative vs. positive A/D breadth

and here's Monday.  This week saw a positive (bullish) A/D line on only 2 days, today being one of them.