AVGO pre-earnings 10-session drift vs post-earnings 10-session returns (last ~3 years)
We tested whether AVGO reliably drifts higher in the ten trading sessions before each quarterly report versus the ten sessions after — the classic pre-earnings run-up thesis — by measuring cumulative 10-day returns around 11 full events over the last ~3 years. That framing matters because a consistent pre-print grind would imply different positioning and risk timing than a strategy that simply holds through the report.
The short answer: the sample is mixed and not statistically decisive. Median pre/post behavior diverges (pre shows positive skew while post medians are closer to flat), but the paired test across 11 events yields t≈−0.38, p≈0.711, so the observed differences are plausibly noise. Full per-event returns, charts, and the t-test details are presented in the analysis below.
For AVGO over the past ~3 years, does the stock systematically drift higher in the ten sessions leading into each quarterly earnings report — the classic 'pre-earnings run-up' — versus its average return in the ten sessions right after? Thesis: AVGO grinds higher into the print as positioning crowds in and then delivers flat-to-choppy returns afterward, so anticipating the report has paid better than holding through it.
How this was measured
Resampled AVGO minute bars to daily closes. From AVGO_earnings, selected quarterly reports with reported_date within the last ~3 years. For each event, anchored t0 as the first trading day on-or-after reported_date. Computed pre-earnings cumulative return over the 10 trading sessions before t0 (t−10..t−1) as close[t−1]/close[t−10]−1 and post-earnings cumulative return over the next 10 sessions (t+1..t+10) as close[t+10]/close[t0]−1. Events without a full 10-day pre and post window were excluded. Paired t-test (ttest_rel) compares per-event pre vs post cumulative returns.
The key numbers
Reading the numbers
Across 11 earnings, the mean 10-day move into the print was +1.53% while the mean 10-day return after was +3.29%. Medians tell a different story (pre +3.68% vs post −0.10%) and the paired test p=0.711 shows no statistically-clear difference.
The charts
This box plot compares the distribution of 10-day cumulative returns before and after the prints. What jumps out is the negative tail on the pre-window (min −17.47%) versus a much larger upside outlier in the post-window (max +23.42%); the means are +1.53% (pre) and +3.29% (post). That pattern says returns are variable: more frequent small positives may occur before the print, but the biggest one-off gains in this sample happened after, so there isn’t a clean, consistent pre-earnings grind-up.
The bar chart puts the averages side by side: the post-earnings mean bar is visibly taller (3.29% vs 1.53%). Visually it might look like holding through the event paid more on average, but remember the paired test p=0.711 — the difference in means is not statistically clear given the 11 events.
The scatter plots each event’s pre 10d return against its post 10d return and the points sit on both sides of the diagonal: some events have strong pre gains (pre max +14.24%) and others show much stronger post moves (post max +23.42%), while negatives happen in both windows (pre min −17.47%, post min −9.37%). That dispersion means there’s no consistent per-event pattern of a systematic run-up into every print — sometimes positioning leads, other times the move comes after.
Earnings events — pre vs post 10-session cumulative returns
| reported_date | anchor_t0 | pre_10d_cum | post_10d_cum |
|---|---|---|---|
| 2023-08-31 | 2023-08-31 | 0.0832 | -0.0318 |
| 2023-12-07 | 2023-12-07 | -0.0684 | 0.2342 |
| 2024-03-07 | 2024-03-07 | 0.0368 | -0.001 |
| 2024-06-12 | 2024-06-12 | 0.0679 | -0.0647 |
| 2024-09-05 | 2024-09-05 | -0.0718 | 0.1802 |
| 2024-12-12 | 2024-12-12 | 0.1424 | 0.1689 |
| 2025-03-06 | 2025-03-06 | -0.1747 | -0.0579 |
| 2025-06-05 | 2025-06-05 | 0.1399 | 0.0034 |
| 2025-09-04 | 2025-09-04 | 0.0375 | 0.0824 |
| 2025-12-11 | 2025-12-11 | 0.0311 | -0.0937 |
| 2026-03-04 | 2026-03-04 | -0.0555 | -0.058 |
The takeaway
No — there’s no clear, reliable pre-earnings run-up for AVGO versus the 10 trading sessions after the report; the sample is mixed and not statistically decisive. Across 11 events the mean 10-session pre-earnings return was +1.53% while the mean 10-session post-earnings return was +3.29%. Looking deeper, the median pre return is +3.68% versus median post -0.10%, and 64% of pre-windows were positive versus 45% post — that pattern shows skew and a few large moves driving means. The paired mean difference (pre − post) is −1.76% with t≈−0.38 and p=0.711, which translates to about a 71-in-100 chance this observed difference is consistent with random noise. Bottom line: the data from the last ~3 years and 11 full events do not give a conclusive edge to anticipating a steady grind higher into earnings; any actionable signal would need more events or a different, intraday-sensitive approach to be convincing.
The fine print
- Only 11 events with full 10-day pre/post windows — thin evidence and sensitive to one or two outlier quarters.
- Anchoring to the next trading day ignores intraday announcement moves and does not capture same-day gaps.
- Using close-to-close 10-session aggregates hides intraday drift and immediate post-release gaps.
- Sample covers roughly the last ~36 months and is regime-sensitive; results may differ outside this window.