BIIB
After each kind of event
| Event | Events | Reaction day | 1 day | 1 week | 1 month | 1 quarter |
|---|---|---|---|---|---|---|
| Any day | 1,255 | — | -0.1%607/1254 up | 0.0%622/1250 up | -0.9%555/1234 up | -0.4%587/1192 up |
| Big drop Oct 28 (-2.3% or worse) | 65 | — | 0.0%33/65 up | -0.1%31/64 up | -1.1%24/64 up | +1.1%32/62 up |
| Big gain (+2.5% or better) | 75 | — | -0.2%34/75 up | -0.9%35/75 up | -1.3%28/73 up | +2.1%37/70 up |
| Earnings beat Oct 28 | 18 | -1.2%6/18 up | +0.4%10/18 up | -0.4%6/17 up | +3.3%11/17 up | +6.7%10/17 up |
| Earnings miss | 2 | -4.1%0/2 up | -0.2%1/2 up | -3.8%0/2 up | -3.3%0/2 up | +2.0%2/2 up |
| 52-week high | 10 | — | -0.6%4/10 up | -0.9%4/10 up | -2.2%4/9 up | +0.3%4/7 up |
| 52-week low | 9 | — | -0.5%4/9 up | -0.9%3/9 up | -6.1%1/9 up | +0.9%5/9 up |
| Crossed above 200-day avg | 3 | — | -2.8%1/3 up | -4.9%0/3 up | +0.5%2/3 up | -0.9%1/3 up |
| Crossed below 200-day avg | 3 | — | +0.3%2/3 up | +1.4%2/3 up | -1.4%1/3 up | -5.6%1/3 up |
| RSI oversold | 15 | — | +0.3%9/15 up | +0.8%10/15 up | -1.4%5/15 up | -5.0%5/15 up |
| RSI overbought | 10 | — | -0.2%5/10 up | -2.4%4/10 up | -1.5%2/9 up | -3.8%3/9 up |
| Volume spike | 12 | — | -0.6%5/12 up | +0.7%7/12 up | -0.5%4/12 up | -5.0%3/11 up |
| Theme selloff hindsight | — | — | — | — | — | — |
| Theme rally hindsight | — | — | — | — | — | — |
| Mention spike (Trendy) | — | — | — | — | — | — |
| Analyst upgrade | 7 | — | -0.3%3/7 up | +5.3%6/7 up | +4.6%6/6 up | +15.7%5/5 up |
| Analyst downgrade | 2 | — | +0.7%2/2 up | +3.1%1/2 up | +8.2%2/2 up | +13.9%2/2 up |
| Insider buy | — | — | — | — | — | — |
| Insider unplanned sale | — | — | — | — | — | — |
Median gain from the close of the session the event was known, over each holding period; Reaction day (earnings only): the session that first traded on the report, from the close before it; under it, how many of the past events were followed by a gain (12/20 up). "Big" is BIIB's own: its worst / best 10% of days over the prior 2 years. Highlighted: happening in the latest session.
Volume spike
Volume at least 3x the prior 20 sessions' average.
| Holding | Events | Median | Up | vs SPY | Range of outcomes (worst · 25–75% · median · best) | vs S&P 500 stocks (their medians) |
|---|---|---|---|---|---|---|
| 1 day | 12 | -0.57% | 5 of 12 | -0.85% |
-7%
+5%
|
|
| 1 week | 12 | +0.71% | 7 of 12 | +0.28% |
-7%
+6%
|
|
| 1 month | 12 | -0.52% | 4 of 12 | -2.36% |
-13%
+8%
|
|
| 1 quarter | 11 ≈9 indep. | -5.04% | 3 of 11 | -6.14% |
-26%
+5%
|
Range of outcomes: all of BIIB's volume spikes in the past 5 years, from the worst to the best result over each holding period; the box holds the middle half, the tick is the median. A wide box means the median alone says little. Hover the median for the average.
Volume spike by trend
| When it happened | Events | 1 day | 1 week | 1 month | 1 quarter |
|---|---|---|---|---|---|
| Long trendAbove its 200-day avg now | 5 | -1.1%5 events vs +0.1% | +1.2%5 events vs +0.5% | +0.5%5 events vs +2.6% | +0.2%4 events vs +6.3% |
| Below its 200-day avg | 5 | +0.9%5 events vs -0.1% | +2.5%5 events vs -0.4% | -0.5%5 events vs -2.7% | -11.0%5 events vs -7.1% |
| Medium trendAbove its 50-day avg now | 6 | +0.4%6 events vs -0.1% | +2.3%6 events vs +0.2% | -0.2%6 events vs +0.4% | -11.0%5 events vs +4.5% |
| Below its 50-day avg | 5 | -1.6%5 events vs 0.0% | +0.3%5 events vs -0.1% | -3.1%5 events vs -1.7% | -2.8%5 events vs -3.1% |
| Short trendAbove its 20-day avg now | 4 | -2.8%4 events vs -0.1% | -4.8%4 events vs -0.3% | -4.9%4 events vs +0.3% | -11.7%4 events vs +3.0% |
| Below its 20-day avg | 8 | +0.6%8 events vs 0.0% | +1.9%8 events vs +0.2% | -0.4%8 events vs -1.7% | -2.8%7 events vs -3.6% |
The same event split by where BIIB stood against its 200-, 50- and 20-day averages when it happened (a dip in an uptrend vs a falling knife); "vs" is the plain any-day median in that trend; "now" marks where it stands today. Splitting halves the evidence: each cell shows how many past events it rests on.
Latest volume spikes
| Event | Entry | 1 day | 1 week | 1 month | 1 quarter | |
|---|---|---|---|---|---|---|
| Sep 18, 2026 | Sep 18 @ $215.50 | 3.7x average volume, -1.6% on the day | +1.7% | +5.6% | +8.3% | … |
| Dec 19, 2025 | Dec 19 @ $174.80 | 7.4x average volume, +2.9% on the day | -0.1% | +1.2% | -0.6% | +5.2% |
| Dec 20, 2024 | Dec 20 @ $146.47 | 3.9x average volume, -0.6% on the day | +2.0% | +2.5% | -0.2% | -2.8% |
| Sep 20, 2024 | Sep 20 @ $199.36 | 4.6x average volume, -1.0% on the day | -1.8% | -2.4% | -7.4% | -26.1% |
| Jun 21, 2024 | Jun 21 @ $224.00 | 3.1x average volume, -0.7% on the day | +1.2% | +3.5% | +0.1% | -11.0% |
| Feb 13, 2024 | Feb 13 @ $226.65 | 3.6x average volume, -7.4% on the day | -2.6% | -2.4% | -3.1% | +0.1% |
| Dec 15, 2023 | Dec 15 @ $248.13 | 3.7x average volume, -3.3% on the day | +0.9% | +4.0% | -0.5% | -11.9% |
| Jan 6, 2023 | Jan 6 @ $279.25 | 3.6x average volume, +2.8% on the day | -1.6% | +3.1% | +4.4% | +1.3% |
| Nov 30, 2022 | Nov 30 @ $305.17 | 3.4x average volume, +4.7% on the day | -1.1% | -4.3% | -9.3% | -11.4% |
| Sep 28, 2022 | Sep 28 @ $276.61 | 16.7x average volume, +39.9% on the day | -4.5% | -5.4% | +0.5% | -0.9% |
| Jan 12, 2022 | Jan 12 @ $225.34 | 4.3x average volume, -6.7% on the day | +5.0% | +0.3% | -4.8% | -5.0% |
| Dec 29, 2021 | Dec 29 @ $258.31 | 5.0x average volume, +9.5% on the day | -7.1% | -7.4% | -12.8% | -18.3% |
Aftermath: entry is the close of the first session the event was fully known (the same session for price moves, the reaction session for earnings, the next session for Reddit, analyst and insider events, which are dated by day). Repeats within a few sessions count as one event. This is history, not a forecast: in our backtests, how a stock did after its past events did not predict its next one. Not advice.