Volatility

Standard Deviation

By Ryan Silk & Lawrence Polatchek · Reviewed April 2026 · Options Trading Glossary

Statistical measure of return dispersion

What is Standard Deviation?

Standard Deviation A statistical measure of the dispersion of returns around the mean. In options, one standard deviation move covers approximately 68% of expected outcomes. The expected move at expiration roughly equals the stock price times implied volatility times the square root of time to expiration.

Complete Definition

A statistical measure of the dispersion of returns around the mean. In options, one standard deviation move covers approximately 68% of expected outcomes. The expected move at expiration roughly equals the stock price times implied volatility times the square root of time to expiration.

Example

A stock at $100 with 20% annual IV has a one standard deviation daily move of about $1.26 ($100 * 0.20 / sqrt(252)).

Related Terms

Variance Implied Volatility Expected Move Probability Of Profit

Written by

ApexVol Research Team

Quantitative options research

All calculations use live ORATS institutional data — the same source used by professional volatility desks.

Technical reviewer

Ryan Silk, ApexVol Founder

Reviewed for technical accuracy

10+ years trading options. Built ApexVol's pricing engine, Greeks model, and IV-rank methodology.

This guide is updated as market conditions and ORATS data change. Last revised 2026-05-12. How we research →

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