Prior day's high, low and close
Prior-day levels are some of the most watched prices in SPX. Here's how often the index actually came back to them over almost five years, and the one thing that matters more than the level itself.
What the prior-day levels are
Every session leaves three prices behind: its high, its low and its close. The next morning, traders mark them on the chart. The high and low are where yesterday's buying and selling ran out. The close is where the day settled, and where a lot of trades were marked.
Because so many people watch them, they get talked about as if they pull price toward them. The useful question is simpler: how often does today's range actually reach them?
How often each level gets reached
Across 1,199 sessions since December 2021, SPX traded back through the prior close on 60.5% of days. It reached the prior high on 55.9% and the prior low on 45.4%.
The high was reached more often than the low because the index rose over the period, from about 4,538 to about 7,586. That's a property of this stretch of history, not a rule.
Both levels in one day is rarer than it feels. Only 120 sessions, 10.0%, took out both the prior high and the prior low. And 105, 8.8%, reached neither.
Distance from the open decides most of it
A level isn't "likely" or "unlikely" on its own. What matters is how far away it is when the session opens. Here's each level split by its distance from the open. For the high and low, this counts the days that opened inside yesterday's range; the close counts every day.
Within 0.25% of the open, about 19 points at today's prices, each level was reached roughly 80% of the time. Between 0.25% and 0.5%, about half. Beyond 1%, about 76 points, it dropped to 23% for the close, 17% for the high and 14% for the low.
Near or far tells you more than high, low or close.
When SPX opens beyond a level
Sometimes the session opens past a level: above yesterday's high, or below yesterday's low. That happened 426 times. Price came back to the level it gapped past on 272 of them, 63.8%.
Size matters here too. Gaps under 0.25% came back 78.9% of the time (195 of 247). Gaps of 1% or more came back 22.7% of the time, but that's only 5 of 22 cases, so treat it loosely.
In the Monitor's session record, SPX opened at 7,632.60, about 5 points below the prior low of 7,637.77. That's a gap of under 0.1%, the size that usually comes back.
Five things to keep in mind
- Measure the distance firstHow far is the level from the open, in points and in percent? That number carries most of the history.
- Small gaps tend to come back; big ones usually don'tUnder 0.25%, about 4 in 5 returned. At 1% or more, about 1 in 5.
- Reached isn't the same as respectedThese numbers count touches. A level that gets reached can hold, or price can run straight through it.
- Both sides in one day is rareAbout 1 session in 10 took out both the prior high and the prior low.
- Averages hide the busy daysEvent days like CPI or a Fed decision can move further than an ordinary day. History is a starting point, not a forecast.
About the data: official SPX daily open, high, low and close, 1,199 sessions from December 2021 to September 2026. A level counts as reached if the day's range touched it. Point figures use about 7,600 for today's index level. The Oct 23 example comes from the Monitor's own session record. These are historical frequencies, not predictions. Past results don't predict future results.