SPDR S&P Biotech ETF (XBI) Seasonality
Recurring seasonal patterns for XBI — the calendar windows where SPDR S&P Biotech ETF has historically tended to rise or fall, with the win rate (how often it repeated) and average return for each, based on the last 10 years of price history.
XBI seasonality at a glance
Over the last 10 years, XBI's strongest seasonal window has been May 19 – Jun 8: it ended higher in 10 of 10 years (100% win rate) with an average return of +4.18% across a 20-day hold. On the weak side, XBI has historically declined between Mar 5 – Mar 25, falling in 9 of 10 years (average -4.81%).
In total, our analysis finds 619 recurring seasonal windows for SPDR S&P Biotech ETF — 408 bullish and 211 bearish. The next high-win-rate window, Sep 16 – Oct 6, opens in 5 days. These figures describe historical behaviour only — not a forecast.
XBI's upcoming & recent seasonal patterns
Holding period:10-day20-day30-dayOrdered by season — windows opening soon first, plus a couple of recently completed high-performers. Holding-period colors help you compare durations at a glance.
| Status | Seasonal window | Hold | Avg return | Win rate | This year |
|---|---|---|---|---|---|
| Completedended 31d ago | Jul 12 – Aug 11 | 30d | -1.45% | 80% | -0.60% |
| Completedended 40d ago | Jul 23 – Aug 2 | 10d | -1.94% | 80% | -3.43% |
| Upcomingin 5d | Sep 16 – Oct 6 | 20d | -1.54% | 80% | — |
| Upcomingin 9d | Sep 20 – Sep 30 | 10d | -1.86% | 80% | — |
| Upcomingin 32d | Oct 13 – Oct 23 | 10d | -1.57% | 80% | — |
| Upcomingin 40d | Oct 21 – Nov 10 | 20d | +2.72% | 80% | — |
| Upcomingin 41d | Oct 22 – Nov 11 | 20d | +3.44% | 80% | — |
Win rate = how often the pattern repeated in the same direction. Average return = the mean move across all analysed years. Past performance does not guarantee future results.
Explore XBI seasonality in full
See the seasonal curve chart, filter by win rate and return, and track upcoming windows — free during beta.
XBI seasonality FAQ
What has historically been the best month to buy XBI stock?
Based on the last 10 years of price data, XBI's strongest seasonal window starts in May: May 19 to Jun 8, which ended higher in 10 of 10 years (100% win rate) with an average return of +4.18%. Past seasonal patterns do not guarantee future performance.
What is XBI's strongest seasonal pattern?
XBI's highest-win-rate pattern in our data is the May 19 – Jun 8 window (20-day hold): up in 10 of the last 10 years with an average move of +4.18%.
When has XBI historically performed worst?
XBI's weakest recurring window has been Mar 5 to Mar 25, declining in 9 of 10 years with an average return of -4.81%.
How reliable are XBI's seasonal patterns?
Each XBI pattern is scored by its historical win rate — the share of the last 10 years it repeated in the same direction. XBI currently shows 619 recurring windows (408 bullish, 211 bearish). Seasonality describes historical tendencies only; it is not a prediction, and past performance does not guarantee future results.
What is XBI stock seasonality?
Seasonality is the tendency of a stock to perform in a similar way during the same period each year. By analysing SPDR S&P Biotech ETF's price history across many years, SeasonalityX identifies recurring calendar windows — exact start and end dates — where XBI has repeatedly risen (bullish) or fallen (bearish). Each pattern is scored by its win rate and average return so you can judge how reliable and how strong it has been.
Seasonality is one input among many — it works best alongside your own research and risk management. Learn more in our guide to seasonal analysis and the tutorials.