What is the current XBI expected move?

As of Sep 30, 2026, State Street SPDR S&P Biotech ETF (XBI) has an expected move of 9.03% over the next 30 days, implying a one-standard-deviation price range of $144.19 to $172.81 from the current $158.50. The expected move is derived from at-the-money straddle pricing and represents the market consensus for a ±1σ price move.

What does the XBI expected move mean for traders?

Roughly 68% of outcomes should fall within ±1 expected move and 95% within ±2 under lognormal assumptions, though equity returns have empirically fatter tails than log-normal predicts. Strategies sized to the expected move (iron condors at ±1σ, strangles at ±1.5σ) target the typical outcome distribution; strategies that profit from tail moves (long-vol structures, ratio backspreads) target the tails the lognormal model under-prices.

How is XBI expected move calculated?

The expected move displayed here is derived from at-the-money implied volatility scaled to the chosen tenor: expected move % is approximately ATM IV times sqrt(T / 365), where T is days to expiration. An equivalent straddle-based form: the ATM straddle (call + put at the same strike) is roughly sqrt(2/pi) times spot times IV times sqrt(T/365), so the implied one-standard-deviation move is approximately 1.25 times ATM straddle divided by spot. The two formulations agree once the sqrt(2/pi) constant is reconciled.

State Street SPDR S&P Biotech ETF (XBI) Expected Move

Expected move estimates the probable price range for a given period based on at-the-money options pricing. It reflects the market consensus for volatility over the selected timeframe.

State Street SPDR S&P Biotech ETF (XBI) operates in the Financial Services sector, specifically the Asset Management industry, with a market capitalization near $8.24B, listed on AMEX, carrying a beta of 1.10 to the broader market. SPDR Series Trust - State Street SPDR S&P Biotech ETF is an exchange traded fund launched by State Street Global Advisors, Inc. public since 2006-02-06.

Snapshot as of Sep 30, 2026.

Spot Price: $158.50
Expected Move: 9.0%
Implied High: $172.81
Implied Low: $144.19
Front DTE: 30 days

As of Sep 30, 2026, State Street SPDR S&P Biotech ETF (XBI) has an expected move of 9.03%, a one-standard-deviation implied price range of roughly $144.19 to $172.81 from the current $158.50. Expected move is derived from at-the-money straddle pricing and represents the market's pricing of a ±1σ move. Roughly 68% of outcomes should fall within this range under lognormal assumptions, though empirical markets have fatter tails.

XBI Strategy Sizing to the Expected Move

With State Street SPDR S&P Biotech ETF pricing an expected move of 9.03% from $158.50, risk-defined strategies sized to the implied range structurally target the modal outcome distribution. Iron condors with wings at the ±1σ expected move boundaries collect premium against the ~68% probability that spot stays inside the range under lognormal assumptions; strangles set wider at ±1.5σ or ±2σ target the tails but pay smaller per-trade premium. Long-vol structures (long straddles, ratio backspreads) profit when realized move exceeds the implied move, the inverse trade: they bet against the lognormal assumption itself, capitalizing on the empirically fatter equity-return tails.

How to read the XBI implied-range chart

The shaded range above shows the one-standard-deviation implied price band at each listed expiration, derived from ATM implied volatility scaled to days-to-expiration. The front-tenor expected move is 9.03%, anchoring an implied range of approximately $144.19 to $172.81. Under lognormal assumptions, roughly 68% of outcomes fall inside that band; 95% fall inside ±2σ; 99.7% inside ±3σ. The empirical equity-return distribution has fatter tails than lognormal, so true tail-outcome frequency is moderately higher than these closed-form numbers suggest.

XBI expected move and event pricing

Expected move widens with √time: a 5% 30-day move corresponds to roughly a 2.5% 7.5-day move and a 10% 120-day move. XBI term-structure is in backwardation (slope -0.001), so near-dated tenors price in disproportionate vol - usually because of a known event in the front-month window.

Sizing XBI structures to the expected move

Iron condors with wings at ±1σ collect the modal-outcome premium; ±1.5σ widens probability of inside-range to ~87% but cuts collected premium roughly in half. Strangles do the inverse trade - they pay against the same lognormal distribution, profiting when realized exceeds implied. Calendar spreads bet on the slope of the term structure rather than the level. XBI put/call volume ratio currently at 2.94 indicates protective put flow dominates - look for hedged-money positioning into the move. The expected move is the inputs the chain is pricing, not a forecast - realized moves above or below are normal under any distribution.

Learn how expected move is reported and how to read the data →

Shaded band shows the ±1σ implied price range (~68% probability under lognormal assumptions) at each expiration; the center line marks current spot. Bands widen with longer DTE since volatility scales with √time.

Per-expiration expected move for XBI derived from ATM implied volatility at each listed expiration. Implied high/low bounds are computed as $158.50 × (1 ± expected move %). One standard-deviation range under lognormal assumptions, roughly 68% of outcomes fall inside.

Expiration	DTE	ATM IV	Expected Move	Implied High	Implied Low
Oct 2, 2026	2	38.2%	2.8%	$162.98	$154.02
Oct 9, 2026	9	31.9%	5.0%	$166.44	$150.56
Oct 16, 2026	16	31.5%	6.6%	$168.95	$148.05
Oct 23, 2026	23	31.6%	7.9%	$171.07	$145.93
Oct 30, 2026	30	31.5%	9.0%	$172.81	$144.19
Nov 6, 2026	37	31.4%	10.0%	$174.35	$142.65
Nov 20, 2026	51	31.6%	11.8%	$177.22	$139.78
Dec 18, 2026	79	31.4%	14.6%	$181.65	$135.35
Jan 15, 2027	107	31.5%	17.1%	$185.53	$131.47
Mar 19, 2027	170	32.0%	21.8%	$193.11	$123.89
Jun 17, 2027	260	31.1%	26.2%	$200.10	$116.90
Dec 17, 2027	443	31.8%	35.0%	$214.03	$102.97
Jan 21, 2028	478	32.2%	36.8%	$216.91	$100.09
Dec 15, 2028	807	32.4%	48.2%	$234.86	$82.14
Jan 19, 2029	842	32.4%	49.2%	$236.50	$80.50

Frequently asked XBI expected move questions

What is the current XBI expected move?: As of Sep 30, 2026, State Street SPDR S&P Biotech ETF (XBI) has an expected move of 9.03% over the next 30 days, implying a one-standard-deviation price range of $144.19 to $172.81 from the current $158.50. The expected move is derived from at-the-money straddle pricing and represents the market consensus for a ±1σ price move.
What does the XBI expected move mean for traders?: Roughly 68% of outcomes should fall within ±1 expected move and 95% within ±2 under lognormal assumptions, though equity returns have empirically fatter tails than log-normal predicts. Strategies sized to the expected move (iron condors at ±1σ, strangles at ±1.5σ) target the typical outcome distribution; strategies that profit from tail moves (long-vol structures, ratio backspreads) target the tails the lognormal model under-prices.
How is XBI expected move calculated?: The expected move displayed here is derived from at-the-money implied volatility scaled to the chosen tenor: expected move % is approximately ATM IV times sqrt(T / 365), where T is days to expiration. An equivalent straddle-based form: the ATM straddle (call + put at the same strike) is roughly sqrt(2/pi) times spot times IV times sqrt(T/365), so the implied one-standard-deviation move is approximately 1.25 times ATM straddle divided by spot. The two formulations agree once the sqrt(2/pi) constant is reconciled.