SPX reference page

Direction Cheat Sheet

A clean summary of the price-only directional stats we checked on SPX. The short version: gap alone is weak, first 30 minutes helps, first hour helps more, and the level context matters.
Back to levels Hub Straddle stats Table Cheat sheet
Best simple signal
First hour
Up first hour closed up 73.1% of the time. Down first hour closed down 68.8%.
Useful but weaker
First 30 min
Up first 30 min closed up 66.1%. Down first 30 min closed down 61.8%.
Main read
Gap + trend
Gap by itself is weak. Gap and first hour agreeing is the cleanest tilt.

Open hierarchy

Strong bullish mean reversion
Open below prior day low or below weekly open. Those are the best open-time long setups in this sample.
Mild bullish continuation
Open above prior day high. Useful, but not nearly as strong as downside mean reversion.
Weak by itself
Gap direction alone and prior-day direction alone do not tell you much.
VIX note
VIX-at-open coverage was too sparse in the cached files to trust as a standalone rule here.

Practical cheat sheet

1. Ignore the gap by itself.
Gap up was only a small bullish edge. Gap down was close to coin-flip.
2. Watch the first 30 minutes.
If the first 30 min is green, the day usually stays green. If it is red, the day usually stays red.
3. Trust the first hour more than the first 30 minutes.
The first hour gave the cleanest directional tilt in the sample.
4. Add level context.
A strong first hour up was usually enough to keep the close above weekly open and prior close.

Fast interpretation

Bullish tilt
Gap down or small gap, then first 30 min green, especially if first hour stays green and price holds above prior close or weekly open.
Bearish tilt
Gap up, then first 30 min red, especially if first hour stays red and price loses prior close.
This is a directional bias tool, not a trading system. It is most useful as a filter for whether to press longs, press shorts, or stay patient.

Reference table

Samples are the same ones we discussed in chat. Weekly open here means the first trading day open of that calendar week.
Signal Sample Up / green result Down / red result Read
Gap direction alone 1,556 days Gap up -> close up 55.5% Gap down -> close down 47.7% Weak by itself
First 30 min 1,056 days First 30m up -> day up 66.1% First 30m down -> day down 61.8% Useful
First hour 1,056 days First hour up -> day up 73.1% First hour down -> day down 68.8% Best simple direction signal
Gap + first hour aligned 1,556 days Gap up + first hour up -> up day 70.3% Gap down + first hour down -> down day 69.6% Better than gap alone
First 30m up vs levels 1,055 days Close above weekly open 69.2%
Close above prior close 70.7%		 Down 30m still above weekly open 52.6% Green 30m usually keeps the day above key levels
First hour up vs levels 1,055 days Close above weekly open 73.7%
Close above prior close 75.1%		 Down hour -> above weekly open 47.9%
Above prior close 43.2%		 Strongest of the bunch

Right at the open

This is the market-open bucket study on SPX RTH bars. `Day up` means the day closed at or above the open.
Open-time signal Sample Day up Day down Read
Gap up vs prior close 525 days 55.2% 44.8% Modest bullish tilt
Gap down vs prior close 407 days 63.9% 36.1% Often mean-reverts higher
Open above prior day high 285 days 55.8% 44.2% Continuation bias, but not huge
Open inside prior range 567 days 63.5% 36.5% Basically the market's normal state
Open below prior day low 203 days 75.9% 24.1% Strongest bullish mean-reversion signal
Open above weekly open 418 days 53.6% 46.4% Small bullish tilt
Open below weekly open 450 days 72.2% 27.8% Usually bounces back above the open
VIX-at-open was too sparsely populated in the cached daily files to be worth hanging a rule on. The price levels above are the ones that actually held up.

Open + first 30 min

This is the most actionable matrix: where the open lands relative to the prior day, then what the first 30 minutes does.
Setup Sample Day up Day down Read
Open below prior low + first 30m up 144 93.1% 6.9% Best long setup in the sample
Open below weekly open + first 30m up 327 85.9% 14.1% Strong long bias
Open inside prior range + first 30m up 378 75.9% 24.1% Good long confirmation
Open above prior high + first 30m down 123 39.8% 60.2% Best short setup in the sample
Open below weekly open + first 30m down 123 35.8% 64.2% Short bias, but weaker than the long bounce cases
Open below prior low + first 30m down 59 33.9% 66.1% Rare, but usually still a down day if it stays red
If you want one actual rule: open outside the prior day range, then wait 15-30 minutes. Reclaiming green after a weak open is the best long trigger I found.

Simple scorecard

This is the compact version if you want a daily decision rule that stays tied to the actual stats.
Condition Score Why
Open below prior day low +2 Strong bullish mean reversion location
Open below weekly open +1 Still bullish, but a bit weaker than prior-low open
First 30m turns green after weak open +2 Best confirmation for longs
Open above prior day high -1 Continuation tilt, but weak
First 30m stays red after strong open -2 Best confirmation for shorts
Score +3 or higher
Long
Best when open is weak and the first 30m reclaims green.
Score -2 or lower
Short
Best when open is strong and first 30m stays red.
Between
Wait
Mixed open or mixed first 30m means chop risk is higher.
The score is intentionally simple. It is not trying to be clever, just to reflect the asymmetry in the sample.

How to use it

Long bias
Gap down or flat, first 30 minutes green, first hour still green, and price holding above prior close or weekly open.
Short bias
Gap up, first 30 minutes red, first hour still red, and price losing prior close.

Notes

- Gap alone is not enough to call direction reliably.
- First 30 minutes is decent. First hour is better.
- If first hour and gap disagree, the first hour usually wins.
- This page is meant as a quick reference, not a full model.