Probability of Profit Explained: A Put Seller's Guide to POP

The number that gets used to justify everything

Open any retail options platform and there is a Probability of Profit reading on every trade ticket, usually a single percentage near the breakeven. Seventy-eight percent. Eighty-six. Ninety-one. Easy to read, easy to misread.

POP is one of the most useful pieces of information on a short-put ticket. It is also one of the most over-trusted. Used well it anchors expectations. Used badly it becomes the entire justification for selling contracts that should not have been sold.

What POP measures

POP estimates, at the moment of entry, the probability that the position will be profitable at expiration. For a short cash-secured put, that means the underlying closing at or above the breakeven price, which is the strike minus the credit received.

The estimate comes from the same pricing assumptions underpinning most retail option models. It takes the current price, the strike, the time to expiration and the implied volatility, and returns a probability that price sits above a given level at expiry. Platforms differ on details, some using mid prices and some using marks, but the spine is the same.

Three features matter.

POP is a point-in-time estimate, computed against today's price and today's volatility. Run it tomorrow with different inputs and you get a different number.

POP assumes the position is held to expiration, which is how our own scoring treats every contract. Processes that close early at a profit target produce a different realised win rate from the entry-day POP, generally higher, because early closures remove winners before they can round-trip. Comparing a held-to-expiry figure against a managed one is comparing two different things.

And POP measures the chance of closing above breakeven, which sits just below the strike. That is worth knowing when you read the number. It is not how we record outcomes. A contract that expires in the money is a loss, full stop. Measuring it any other way makes a strategy's numbers look better than they are by quietly reclassifying its losses.

POP and delta

A quick approximation every put seller should know. For a short out-of-the-money put:

POP ≈ 1 + delta

Delta on a short put is negative. A 0.20-delta short put gives a POP of roughly 0.80, or 80%. A 0.30-delta short put gives roughly 0.70. Close enough for back-of-the-envelope reasoning and within a few points of what a real pricing engine returns.

This is why the two are tightly coupled. A lower delta strike, further out of the money, raises POP and lowers the credit. A higher delta strike does the reverse. You are picking a point on a curve.

Two caveats. The approximation tightens as expiry approaches, because on long-dated contracts the distribution has more room to wander. And delta approximates the probability of expiring in the money rather than below breakeven, so POP is slightly higher than 1 plus delta. For most purposes that is a rounding error.

Why high POP is not a high win rate

A 90% POP at entry does not mean a 90% chance of the trade being a winner in lived experience. The gap has several sources.

The size of the loss. The 10% that does not finish profitable does not finish at zero. A short put that goes deep in the money can lose multiples of the credit collected. A process of selling 90% POP contracts and holding them wins nine times and loses once, and that one loss can exceed the nine wins combined. Expected value is the win rate weighted by the size of wins and losses, not the win rate alone.

Volatility regime. POP is computed against current implied volatility. When volatility is compressed the model assumes the underlying will not travel far, so distant strikes show very high POP. When it expands, the same strikes look considerably riskier. A comfortable 90% can become an uncomfortable 75% a week later without the seller doing anything.

Path. POP describes the closing price at expiration. It says nothing about what happens on the way there. A position the model correctly predicts will close profitably can travel through the strike beforehand, and plenty of sellers exit at the worst moment because of it.

Journaling. Sellers remember wins and underweight the size of losses. A book with a high win rate and one very large loss buried in it is the rule rather than the exception.

Reading it better

POP works best as one input in a three-part read.

The first is POP itself: what does the model say about finishing above breakeven?

The second is distance in standard deviations. How far does the strike sit below the underlying given current volatility and time remaining? This is the continuous version of the same idea POP captures as a single number.

The third is the historical floor. Where has the underlying actually moved in comparable conditions? A strike that looks statistically comfortable means little if the underlying has repeatedly travelled through that level.

When the three agree, the trade has a coherent profile. When they disagree, particularly when the statistical reading looks fine but the historical floor sits below the strike, that is a cue to look harder. The high POP is not wrong. It is incomplete.

How StratosIQ handles it

There is no single POP number on a contract here, because the platform treats POP-equivalents as components rather than as a headline.

The geometry POP describes, how far the strike sits from the underlying and how likely that distance is to hold, feeds the score. So does the return the contract offers against the capital it locks up, and the quality of the execution available.

What dominates the score is safety, and safety is measured against a floor built from how the underlying has actually behaved rather than from a pricing model alone. That floor comes from ShieldIQ, reported as Fortified, Secure, Tight or Exposed. A contract can look excellent on statistical distance and still be rejected because its floor is thin, which is precisely the correction most POP-driven processes are missing.

Since March 2026, the highest-scored contract published each day has finished out of the money 93.3% of the time, across 208 contracts. That is a held-to-expiry figure with no early closures in it, which makes it directly comparable to the entry-day POP idea rather than inflated by management. The record is on the performance page.

For the volatility side of the same question, IV Rank covers whether the premium being paid is rich relative to the underlying's own history.