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 $8.33B, 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 Aug 14, 2026.

Spot Price

$157.35

Expected Move

7.8%

Implied High

$169.66

Implied Low

$145.04

Front DTE

28 days

As of Aug 14, 2026, State Street SPDR S&P Biotech ETF (XBI) has an expected move of 7.82%, a one-standard-deviation implied price range of roughly $145.04 to $169.66 from the current $157.35. 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 7.82% from $157.35, 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 7.82%, anchoring an implied range of approximately $145.04 to $169.66. 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 contango (slope 0.017), so longer-dated tenors price in proportionally more vol than √time scaling alone would suggest - typically because long-dated cycles include uncertain macro states. With IV rank at 20.7%, the implied move is at the low end of the typical XBI range - cheap optionality for buyers, thin premium for sellers.

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 2.42 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 →

Per-expiration expected move for XBI derived from ATM implied volatility at each listed expiration. Implied high/low bounds are computed as $157.35 × (1 ± expected move %). One standard-deviation range under lognormal assumptions, roughly 68% of outcomes fall inside.

Frequently asked XBI expected move questions

What is the current XBI expected move?

As of Aug 14, 2026, State Street SPDR S&P Biotech ETF (XBI) has an expected move of 7.82% over the next 28 days, implying a one-standard-deviation price range of $145.04 to $169.66 from the current $157.35. 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.