SPX 0DTE Trading: What Violent 15-Minute Candles Tell You About the Close

A large move in a single 15-minute candle often feels like it should influence the rest of the session. We tested whether these moves carry meaningful directional information by examining every 15-minute bar in the S&P 500 since mid-2020 and measuring how the index performed from the end of that bar through the 4 PM close.

The results show a modest but consistent pattern: sharp up-moves tend to see mild follow-through into the close, while sharp down-moves are more likely to stabilize than extend.

Up-Moves Show Modest Continuation

Up move in one bar	Samples (days)	Avg to close	Median	Closed higher
0.75%	61 (43)	+0.65%	+0.21%	57%
0.50%	229 (157)	+0.26%	+0.21%	59%
0.25%	1,557 (682)	+0.07%	+0.07%	54%

Down-Moves Tend to Stabilize

Down move in one bar	Samples (days)	Avg to close	Median	Closed higher
0.75%	68 (50)	+0.27%	+0.08%	51%
0.50%	280 (191)	+0.18%	+0.08%	53%
0.25%	1,743 (728)	+0.02%	+0.02%	52%

The drift is tiny next to the day's range

Before anyone builds a system on this, look at the size of the edge. The biggest average in the whole study is 0.65%, after the rarest event (a 0.75% up-bar, which happened on just 43 days in six years).

At the 0.25% cutoff, where the sample swells well past a thousand bars, the average forward move is under a tenth of a percent in either direction. That is a rounding error on a typical S&P session.

How much of this is just the market going up

The positive results in both tables have a quieter explanation: the S&P drifted higher on balance across the 2020 to 2026 period, even with the 2022 bear market in the middle, so random afternoon moves carried a mild positive bias regardless of what happened in the prior 15 minutes. That structural drift accounts for much of the follow-through after up-bars and is also why down-bars still closed higher rather than flat.