Implied vs realized volatility: compare horizons and risk

Compare implied and realized volatility over matched horizons. A historical gap provides context but does not guarantee profit on a short option.

By OptionsKing. Publisher and editorial methods.

Today's IV is a price for future exposure; trailing realized volatility measures an earlier period. Begin with that timing difference. The repricing example then shows sensitivity to an assumed volatility change, which is distinct from a forecast of the actual trade's profit.

Just under two volatility points. That is the whole edge, and every seller reading this should sit with how small it is.

What two points is worth in money

Take the 45-day $74 straddle, which is the cleanest way to price pure volatility.

• Sold at 26 percent implied: $540.
• What it would be worth at 24.1 percent: $501.
• Difference: $39, or 7.2 percent of the credit.

So the theoretical edge on a straddle you are risking real money on is thirty-nine dollars. Widen the bid-ask spread by four cents a leg and a fifth of it is gone before you have taken any risk at all.

That is not an argument against selling premium. It is an argument against sloppiness, and it explains why the difference between good and bad execution matters more in this strategy than the difference between good and bad forecasting.

Why the gap exists

Options are insurance and insurance costs more than it pays. That is not a market failure, it is the entire business model of insurance.

The demand side is structural and it barely cares about price. Pension funds hedge. Portfolio managers buy puts in size before they need them, because explaining an unhedged drawdown is career-ending in a way that explaining a hedging cost is not. Covered-call funds sell calls on a schedule. Retail buys lottery-ticket calls. Not much of that flow is trying to make money on the option itself, which is why the price of protection stays above its statistical value.

You, selling puts on Nike, are on the other side of that. You are paid a premium for holding a risk somebody else is contractually obliged to shed. It is a real economic function and it deserves a real return.

The comparison mistake almost everyone makes

A volatility-point gap is not the same unit as a variance risk premium: variance is volatility squared. Nor does repricing a straddle at a lower volatility establish the return on holding it. Label the calculation and record realized trade outcomes separately.

Here is the thing that makes the variance risk premium look bigger than it is.

You cannot compare today's 30-day implied against the last 30 days realized. Those measure two different periods. Today's implied is a price on June 3 through July 3. Trailing realized covers late April through June 3. Putting them side by side and declaring the option expensive is comparing a forecast of next month against a measurement of last month, and it will systematically flatter you in calm markets and destroy you at turning points.

The correct comparison needs the future. You sell at 26 percent on June 3, wait until the contract expires, then compute what the stock realized over that window. This gives a matched-horizon outcome for the volatility comparison. It does not by itself prove an ex-ante trading edge or determine an unhedged option's total P/L.

If you want one habit out of this page: keep the implied you sold at, in a column, next to the realized that followed. After forty trades you will know your own edge instead of quoting somebody else's.

When the gap inverts

Implied above realized is a tendency, not a rule, and the exceptions are not randomly scattered. They cluster, and they cluster on exactly the days a short book is largest.

• Scheduled events. The 30-day implied on Nike is 41 percent, not 26, because June 26 sits inside it. That 41 is not a free 17 points of edge. It is the market pricing a gap it can see on a calendar. Sometimes it overprices it, and sometimes it does not.
• Regime breaks. Realized volatility can triple in a week. Implied is quoting the world as of this morning, and in the first days of a real dislocation it is behind, not ahead.
• Names in trouble. A stock in a merger fight or a solvency scare has a distribution nothing continuous describes, and the option was priced by someone who knows that better than you do.

A positive average risk premium can coexist with severe clustered losses. A volatility-point difference is not a cash P/L formula: exposure, path, hedging, and position size determine how changes translate into money. Stress the tails rather than assuming a stable two-point gain.

Common questions

Sources

• OCC, Characteristics and Risks of Standardized Options

Rules and thresholds above were checked against these documents on August 4, 2026. Exchange and broker rules change. Confirm anything you are about to act on with your own broker.

Keep reading

• What the implied number is made of
• Computing the other side of the comparison
• The one date where the gap is largest and least free

Do the math on your own trade

• Implied volatility calculator solve for IV from a market price, and get the move it implies.
• IV rank calculator whether today is actually a high-premium day.
• Annualized return calculator turn any credit and any holding period into a yearly rate.

Every price in this article is an illustrative worked example, not a quote. Read Volatility for the rest of the series, and the disclaimer before you act on any of it. Selling options carries real risk of loss, and the loss can be far larger than the premium you collected.