Every options trade is, at its core, a volatility trade. The buyer is paying for the possibility of a large move. The seller is collecting a premium for absorbing that risk. The question that determines who profits is not "which direction will the stock move?" but "will the stock move more or less than the option's price implies?"

This question is the difference between implied and realized volatility. Understanding it changes how you evaluate every options position you consider.

Implied volatility: the market's forecast

Implied volatility (IV) is not something you observe directly. It is derived from the option's market price by working backward through a pricing model (typically Black-Scholes or a variant). Given the stock price, strike price, time to expiration, risk-free rate, and the option's current market price, IV is the volatility number that makes the model's theoretical price match the actual market price.

In plain terms, IV represents the magnitude of the move that the market is currently pricing into the option. If a stock trades at $100 and the 30-day implied volatility is 30%, the market is pricing roughly a $9.50 move (one standard deviation) over the next 30 days. The option premium reflects the cost of being exposed to that potential move.

IV is forward-looking. It is an expectation, not a measurement. And like all expectations, it can be wrong.

Realized volatility: what actually happened

Realized volatility (RV), also called historical or statistical volatility, is the actual standard deviation of the asset's daily returns over a specified period. It is purely backward-looking. After the 30 days pass, you can calculate exactly how much the stock actually moved.

If the 30-day IV was 30% when you entered the trade and the 30-day realized volatility turned out to be 20%, the option was overpriced. The market expected a bigger move than what occurred. Option sellers profited. Option buyers overpaid.

The volatility risk premium

Here is the most important structural fact in options markets: implied volatility exceeds realized volatility most of the time. This is not a glitch. It is a well-documented phenomenon called the Volatility Risk Premium (VRP).

Over the six-month period from September 2025 through March 2026, SPY's implied volatility exceeded its realized volatility on approximately 78% of trading days, with a median premium of roughly 2.9 percentage points. This means that on most days, options were priced for a bigger move than what actually occurred.

The VRP exists for the same reason insurance premiums exceed expected losses: option sellers are taking on tail risk (the possibility of a sudden, outsized move), and they demand compensation for that risk. Most of the time, the tail event does not occur, and the seller keeps the premium. Occasionally it does occur, and the seller absorbs a large loss. Over time, the premium is expected to compensate for those occasional losses.

The VRP is the structural edge that makes option selling profitable over long periods. But it is not free money. It is compensation for absorbing the risk of the moves that options are designed to protect against.

Why IV Rank is not enough

The most popular retail framework for evaluating implied volatility is IV Rank, which compares current IV to its own 52-week range. If IV hit a low of 15% and a high of 45% over the past year, and current IV is 30%, the IV Rank is 50%. This tells you whether IV is high or low relative to its own recent history.

The problem is that IV Rank ignores realized volatility entirely. A stock with an IV Rank of 70% might still have a negative VRP if realized volatility has been even higher. During the tariff-driven market stress of early March 2026, SPY IV spiked to 29.6%. IV Rank was extremely elevated, which under the standard framework would signal "sell premium." But realized volatility was also spiking, and the spread between IV and RV compressed dramatically. Selling into that environment delivered the thinnest margins and the ugliest drawdowns of the period.

The professional framework

Professional volatility traders do not ask "is IV high?" They ask "is IV high relative to what I expect realized volatility to be?" This is a fundamentally different question, and it requires a view on future realized volatility, not just a reading of current IV.

The practical application is straightforward. Before entering an options position, compare the current IV to your estimate of future realized volatility. If IV is significantly above your RV estimate, the premium is rich and favors selling. If IV is below your RV estimate, the premium is cheap and favors buying. If they are close, there is no edge, and the best trade may be no trade.

Developing a reliable estimate of future realized volatility is the hard part. It requires understanding the current market regime, upcoming catalysts (earnings, FOMC, economic data), and whether recent realized volatility is likely to persist or mean-revert. This is where the real skill in options trading lives. Not in reading IV Rank from a screener, but in forming an independent view on how much the underlying is actually going to move.

The educational takeaway

Options are priced on expectations. They are evaluated on outcomes. The gap between the two is where edge exists. If you trade options without understanding the relationship between implied and realized volatility, you are trading blind, regardless of how sophisticated your directional thesis might be.