When the index rises and fewer stocks join

In classroom packs we often pair an index making a fresh high with a cumulative advance-decline line that has stalled or rolled over. The point is not to declare a top on the spot. The point is to force a pause: if fewer issues are advancing, who is carrying the print, and is that leadership concentrated enough that a reversal in those names would undo the index move quickly?

What we ask students to mark

On each sample session they annotate four items: the index high date, the A/D value relative to its own prior peak, a rough count of sectors participating, and a one-line judgement — “broad,” “narrow,” or “unclear.” Unclear is allowed. Pretending certainty when the series conflict is not.

A mild caution

Divergence can persist longer than new students expect. We treat it as a participation warning, not an automatic short signal. That distinction keeps the intensive honest about what breadth can and cannot deliver.