As you can see in region (A), the ratio has put in a succession of lower highs and lower lows over the past two months even as the SPX has registered higher prices.
This is a bearish divergence.
This isn’t a timing tool as the market often times puts in multiple % points of additional upside before any pullback occurs.
However, more often than not such degradation of internals does precede pull-backs, as the chart suggests.
The question tends to be “when”, not “if”, such pull-backs are coming.
Impossible to tell when any pull-back occurs, but it does seem internals are suggesting one is on the horizon.