Do Some Weekdays Reverse Harder Than Others?

Day-of-week patterns are among the oldest ideas in market analysis. Concepts like Monday weakness, Turnaround Tuesday all stem from the belief that certain weekdays have a greater tendency to reverse than others.

To test this, we examined roughly 6,300 S&P 500 trading sessions since 2001.

First, the number you have to beat

The S&P drifts higher over time, which means a green day is the default outcome. Across the full sample, with no condition applied, the next session closed green 54.2% of the time. That is the real bar. For any weekday pattern to be meaningful, the following day's green rate must be above 54.2%.

A red day is typically followed by a bounce, and the probability of that reversal shows little variation across weekdays

Weekday	After a green close		After a red close
	Next day green	Next day red	Next day green	Next day red
Monday	49.1%	50.9%	57.1%	42.9%
Tuesday	53.0%	47.0%	57.4%	42.6%
Wednesday	51.1%	48.9%	58.3%	41.7%
Thursday	53.4%	46.6%	56.3%	43.7%
Friday	51.3%	48.7%	56.8%	43.2%

After a red close the next day turned green between 56% and 58% of the time, and it did so on every weekday. That is a few points above the 54.2% baseline, and the gap between the five days is small. What you are seeing is the market's standard tendency to rebound after a down day, spread fairly evenly across the week. A red Wednesday is marginally the best at 58.3%, though not by enough to set it apart.

The one weekday that breaks the rule is a green Monday

Now flip it around: does a green day lead to a red one? On Tuesday, Wednesday, Thursday, and Friday, a green close is followed by another green day at roughly the baseline rate of 54.2%.

Monday is the clear outlier. A green Monday is followed by another green day just 49.1% of the time. It is the only weekday where a green close tips the odds toward red, and at roughly five points below the 54.2% baseline, it stands out as the most notable one-day weekday effect in the results.

Two in a Row Sharpens the Signal

Requiring two consecutive days in the same direction strengthens the pattern. After two green days in a row, the third session closed higher just 51.1% of the time (below the 54.2% baseline). After two red days, the third session rebounded to a 57.5% green rate.

We then examined every possible two-day run of consecutive gains or losses, broken down by weekday, to see which combinations most strongly influence the third day.

Two days in a row	Third day	Third day green	Vs baseline
Fri + Mon, both green	Tue	46.7% (321)	-7.4
Mon + Tue, both red	Wed	60.3% (229)	+6.1
Thu + Fri, both green	Mon	48.1% (351)	-6.0
Wed + Thu, both red	Fri	57.8% (237)	+3.6
Tue + Wed, both red	Thu	57.0% (258)	+2.8
Fri + Mon, both red	Tue	56.6% (219)	+2.5
Thu + Fri, both red	Mon	55.2% (248)	+1.1
Mon + Tue, both green	Wed	54.8% (310)	+0.7
Tue + Wed, both green	Thu	54.7% (353)	+0.5
Wed + Thu, both green	Fri	54.1% (353)	-0.1

Two combinations stand out clearly, and both reinforce the one-day patterns observed earlier.

A green Friday followed by a green Monday produced the weakest follow-through in the study, with Tuesday closing higher just 46.7% of the time. This suggests that the tendency for Monday strength to fade becomes even more pronounced when Friday was also positive.

Conversely, a red Monday followed by a red Tuesday led to the strongest rebound, with Wednesday closing higher 60.3% of the time. This points to a tendency for the market to recover midweek after a weak start to the period.