MARA Monday opening gaps vs Tue–Fri gaps over ~3 years
MARA’s Monday opening gaps are meaningfully larger and more volatile than gaps on the rest of the week: the mean absolute Monday gap is about 3.11% versus 2.17% for Tuesday–Friday (difference ≈0.94 percentage point), and the difference is statistically robust (Welch t p≈0.0003; Levene p≈0.0000). Put simply, weekend bitcoin moves are being compressed into a single repricing at Monday open, and that repricing is both bigger and less predictable than typical weekday openings.
Below you’ll find the full computed study — data window, minute-bar to RTH conversions, the gap-by-weekday comparisons, distributional charts, and formal tests — that support this conclusion and show how extreme moves concentrate on Mondays.
For MARA over the past ~3 years, is the Monday opening gap (Friday close → Monday open) systematically larger and more volatile than the gaps on other weekdays, since the stock sits out the weekend while Bitcoin keeps trading around the clock? Thesis: Monday gaps dwarf Tuesday–Friday gaps in both size and dispersion because the open has to reprice two days of weekend crypto moves at once, so the weekday a gap lands on matters far more than traders assume.
How this was measured
Converted MARA minute bars to New York time and filtered to regular trading hours (Mon–Fri, 09:30–16:00 ET). For each trading day, computed the opening gap as (today's RTH open / prior trading day's RTH close − 1). Monday gaps thus span the full weekend (Fri close → Mon open). Grouped gaps by weekday, compared Monday against Tue–Fri on mean absolute gap (magnitude) via Welch's t-test and on dispersion via Levene's variance test. Window: 2023-05-31 to 2026-05-29 (restricted to last ~3y).
The key numbers
Reading the numbers
Mondays average a 3.11% opening gap versus about 2.17% on Tue–Fri — roughly 0.00938 (0.94 percentage points) larger. That difference is statistically significant (Welch p = 0.00032285) and Monday gaps are measurably more variable (Levene p = 1.5317e-05).
The charts
The box plot shows Monday absolute gaps sit noticeably higher than the other weekdays: Monday mean is 0.0311 with a min of 0.0003 and a max of 0.1896, whereas other days cluster around means near 0.021–0.023. Look at the long Monday whiskers and the extreme Monday max — they indicate more big outliers on Mondays. This visual pattern matches the stats that Monday gaps are both larger on average and more dispersed than Tue–Fri.
The bar chart makes the mean difference easy to see: Monday mean |gap| = 0.0311 versus Tuesday–Friday values of 0.0213, 0.0219, 0.0230 and 0.0208, so Monday is about 0.00938 larger than the Tue–Fri average. Note the sample backing: 138 Mondays versus 594 Tue–Fri days overall, and the mean difference is statistically significant (Welch p = 0.00032285). In short, the weekday the gap falls on matters — Mondays are systematically bigger.
Weekday gap summary (MARA, RTH open vs prior close)
| Weekday | N | Mean gap | Median gap | Std gap | Mean |gap| | Std |gap| |
|---|---|---|---|---|---|---|
| Monday | 138 | 0.0032 | 0.005 | 0.042 | 0.0311 | 0.0283 |
| Tuesday | 151 | -0.0023 | -0.0043 | 0.0297 | 0.0213 | 0.0207 |
| Wednesday | 149 | 0.0051 | 0.0038 | 0.0292 | 0.0219 | 0.0198 |
| Thursday | 145 | 0.0044 | 0 | 0.0323 | 0.023 | 0.023 |
| Friday | 149 | 0.005 | 0.0055 | 0.0279 | 0.0208 | 0.0192 |
The takeaway
Yes — Monday opening gaps for MARA are meaningfully larger and more volatile than gaps on other weekdays. The average absolute Monday gap is about 3.11% versus 2.17% for Tuesday–Friday, a difference of roughly 0.94 percentage points, and Monday signed-gap volatility is ~4.20% vs ~2.99% for the other days (N=138 Mondays, N=594 Tue–Fri). Mondays also make up 18.1% of the top-decile absolute gaps while Tue–Fri collectively account for about 8.25%, so extreme moves are concentrated on Mondays. These differences are statistically robust: the mean-difference test gives p≈0.00032 (only about a 3-in-10,000 chance the magnitude gap is pure luck) and the variance test gives p≈0.000015 (about a 1.5-in-100,000 chance the volatility gap is luck). In plain terms this is a strong, conclusive signal — not a coin flip or a weak lean. Practical takeaway: treat weekend risk as real and larger than intraday weekday risk — expect bigger and more variable re-pricing at Monday open and plan sizing/hedges accordingly.
The fine print
- RTH-only opens ignore premarket trading; heavy premarket activity can make the measured RTH gap understate the true overnight move.
- Tuesdays following Monday market holidays absorb multi-day crypto moves but are classified as Tuesday here, which can inflate non-Monday gaps.
- There are only 138 Mondays in the sample; a few very large weekend moves could disproportionately drive the observed effect.
- Results cover 2023-05-31 to 2026-05-29; different 3-year slices or volatility regimes may change the magnitudes.