Decoding Volatility with the Rule of 16 | Teach Me Like I'm Five

In this episode of our new show Teach Me Like I'm 5, we’re joined by Mat Cashman, Principal of Investor Education at the OCC, to break down a powerful yet often overlooked concept in options trading: the Rule of 16. Whether you're new to volatility or a market veteran, this conversation takes you from the sandbox to the risk desk, explaining how this simple rule transforms annualized volatility into daily insight—and how professionals use it to assess market surprises, portfolio risk, and trading decisions. What We Cover: What the Rule of 16 is and why it matters Translating annualized volatility into daily expectations Why understanding standard deviation helps traders interpret large price moves How experienced traders use the Rule of 16 to adjust to fast-changing volatility Real-world examples including recent five-standard-deviation events The psychological and behavioral impact of “surprising” moves on market participants How to build a daily baseline for expected price movement Using the Rule of 16 to contextualize options positions and risk management Timestamps: 00:00 – “How surprised should you be if it rains?” 00:28 – Welcome and show introduction 01:06 – What is the Rule of 16? 02:08 – Why daily volatility matters more than annual volatility 03:17 – The Rule of 16 explained with a bouncy ball and sandwich 05:00 – Translating implied vol into daily expected movement 07:00 – Volatility as a weather forecast: what to expect, not what will happen 08:33 – How professionals use the Rule of 16 10:00 – Real-life example: 5.6 standard deviation move 12:00 – Crowd reaction and market psychology 13:00 – Adjusting to rising volatility and changing expectations 14:00 – Reaction functions for options traders 15:32 – Beyond the number: context, clues, and dynamic markets 16:52 – Wrap-up and final analogy