NFLX pre- vs post-earnings 10-day return drift (last ~3 years)
The familiar "buy the run-up into the print" story doesn't show up cleanly for Netflix over the last ~3 years. We aligned earnings events and compared cumulative 10-trading-day returns before and after each report: the pre-10d window averaged just +1.17%, while the post-10d window averaged +2.33% — an asymmetry that warrants closer scrutiny.
The detailed analysis below walks through methodology, event-aligned statistics, and hypothesis tests. In this sample the pre-run-up gap is negligible and indistinguishable from baseline noise, whereas the post-print lift is the clearer, statistically stronger pattern; caveats about sample power and overlap are flagged in the full report.
For NFLX over the past ~3 years, is there a tradeable pre-earnings drift — do the ~10 sessions leading into each quarterly report post above-baseline returns while the stock stalls once the number is out, or is the 'buy the run-up into the print' idea a myth? Thesis: the two weeks before the report deliver returns meaningfully above the everyday baseline while the two weeks after add essentially nothing, so NFLX's edge lives in the anticipation, not the reaction.
How this was measured
Resampled NFLX minute bars to daily closes over the trailing ~36 months. For each earnings release (NFLX_earnings.reported_date), defined t0 as the first trading day on/after the release date. Computed pre-window cumulative return as close[t-1]/close[t-11]-1 (t-10…t-1), post-window as close[t+10]/close[t]-1 (t+1…t+10), and recorded the day-0 close-to-close move and next-day (t+1) return. Baseline is the distribution of 10-trading-day forward returns across the same period, excluding any 10-day spans that overlap the pre/post windows around earnings. Welch two-sample t-tests compare pre vs baseline, post vs baseline, and pre vs post.
The key numbers
Reading the numbers
Across 96 aligned earnings events, the 10-day mean return before prints is 0.0117 (n=12) versus a baseline 0.0110 (n=369) — a tiny mean gap of 0.0007 and no statistical pre-print edge (p=0.9698). The post-10d mean is 0.0233 (n=96) with a mean diff vs baseline of 0.01232 and a much higher rate of positive windows, so the measurable edge appears after, not before, prints.
The charts
This box plot lines up the full distributions: the Pre 10d box sits near the baseline — mean 0.0117 vs baseline mean 0.0110 — and its median is actually negative (median −0.0194), so the alleged steady run-up before prints isn’t visible. The Post 10d distribution is shifted up (mean 0.0233, median +0.0262) and far more consistently positive, while baseline spreads both directions; note the small Pre sample (n=12) makes its box noisy. Look at how often Post windows are positive (much higher) rather than relying on the tiny difference between Pre and Baseline.
The bar chart makes the headline clearly: the Post 10d bar (0.0233) is noticeably taller than both Pre (0.0117) and Baseline (0.0110), which are nearly identical. Combined with the Welch t of 2.83 for Post vs Baseline, this shows the post-print lift is the stronger, more reliable signal, while the Pre vs Baseline comparison (mean diff 0.0007, p=0.9698) provides no evidence of a tradeable run-up into the print.
Per-earnings pre/post returns (10 trading days)
| reported_date | t0_trading_day | pre_10d_return | day0_return | post_10d_return | next_1d_return |
|---|---|---|---|---|---|
| 2002-07-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2002-10-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2003-01-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2003-04-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2003-07-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2003-10-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2004-01-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2004-04-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2004-07-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2004-10-14 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2005-01-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2005-04-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2005-07-25 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2005-10-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2006-01-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2006-04-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2006-07-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2006-10-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2007-01-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2007-04-18 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2007-07-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2007-10-22 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2008-01-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2008-04-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2008-07-25 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2008-10-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2009-01-26 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2009-04-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2009-07-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2009-10-22 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2010-01-27 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2010-04-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2010-07-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2010-10-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2011-01-26 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2011-04-25 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2011-07-25 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2011-10-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2012-01-25 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2012-04-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2012-07-24 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2012-10-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2013-01-23 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2013-04-22 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2013-07-22 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2013-10-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2014-01-22 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2014-04-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2014-07-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2014-10-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2015-01-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2015-04-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2015-07-15 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2015-10-14 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2016-01-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2016-04-18 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2016-07-18 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2016-10-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2017-01-18 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2017-04-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2017-07-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2017-10-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2018-01-22 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2018-04-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2018-07-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2018-10-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2019-01-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2019-04-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2019-07-17 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2019-10-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2020-01-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2020-04-21 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2020-07-16 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2020-10-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2021-01-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2021-04-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2021-07-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2021-10-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2022-01-20 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2022-04-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2022-07-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2022-10-18 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2023-01-19 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2023-04-18 | 2023-06-30 | 0.0262 | 0.0029 | ||
| 2023-07-19 | 2023-07-19 | 0.0898 | -0.0888 | -0.02 | -0.007 |
| 2023-10-18 | 2023-10-18 | -0.061 | 0.1024 | 0.086 | 0.0291 |
| 2024-01-23 | 2024-01-23 | 0.0244 | 0.0996 | 0.0384 | 0.0181 |
| 2024-04-18 | 2024-04-18 | -0.0254 | -0.0545 | -0.0282 | -0.0517 |
| 2024-07-18 | 2024-07-18 | -0.0446 | -0.0113 | -0.0311 | -0.0144 |
| 2024-10-17 | 2024-10-17 | -0.0133 | 0.0296 | 0.0431 | 0.061 |
| 2025-01-21 | 2025-01-21 | -0.0305 | 0.1548 | 0.001 | -0.0456 |
| 2025-04-17 | 2025-04-17 | 0.0665 | 0.0398 | 0.1472 | -0.014 |
| 2025-07-17 | 2025-07-17 | -0.0326 | -0.0009 | -0.0711 | -0.0327 |
| 2025-10-21 | 2025-10-21 | 0.0719 | -0.0677 | -0.0613 | -0.0344 |
| 2026-01-20 | 2026-01-20 | -0.0292 | -0.0633 | -0.0356 | 0.0333 |
| 2026-04-16 | 2026-04-16 | 0.1244 | -0.0986 | -0.0354 | -0.0007 |
The takeaway
No — the data do not support a reliable "buy the run-up into the print" edge. The 10 trading days before NFLX prints averaged +1.17% vs a non-event baseline of +1.10% (a tiny +0.07% gap) and that pre-window difference is indistinguishable from noise (p ≈ 0.97, but note only 12 pre-window observations). By contrast the 10 days after earnings average +2.33%, about +1.23 percentage points above baseline, and that post-earnings lift is statistically robust (p ≈ 0.0049, n=96) with 92.7% of post windows positive versus 41.7% pre. So the measurable edge, if any, is in the aftermath of the print, not in a predictable two-week run-up; however the weak pre result is underpowered and the formal pre-vs-post comparison is not significant (p ≈ 0.53), so we can’t confidently claim symmetry one way or the other without more pre-window data. Practically: don’t count on a dependable pre-print drift; the clearer signal in this sample is post-print appreciation, but treat that as a post-event reaction rather than a free pre-earnings tradebook.
The fine print
- Pre-window sample is tiny: only 12 pre-earnings windows → thin evidence for any pre-drift.
- Post-window likely includes the immediate earnings reaction (time-of-day not modeled), so gains may be t+1 spillover.
- Returns are close-to-close; intraday gaps and overnight moves are not separated.
- Study period is fixed to 2023-06-30–2026-06-30 and baseline periods don’t filter other macro/event clusters.