Taking Profits at 50%: The Math Behind Knowing When to Close

The rule

Here is one of the simplest rules in our entire operation: when a short option has decayed to half the premium we collected, we close it. Sell for $4.00, buy back at $2.00, keep the difference. Bank it, move on, sell the next one.

It sounds almost too simple to matter. It is not. It is the single highest-leverage trade-management decision we make — and we have the receipts to show it.

Why the first half is the easy half

Options lose value as time passes. That decay — theta, in the jargon — is the engine of every premium-selling strategy. But the decay is not linear. It is front-loaded: an option loses its value fastest in the weeks right after you sell it, and the last crumbs of premium take the longest to disappear.

Think of it like squeezing a sponge. The first squeeze gets most of the water. The second, third, and fourth squeezes get less and less, and your hands get tired. Closing at fifty percent is the first squeeze. You capture the fast, easy half of the decay — the part that took the least time and carried the least drama.

Now consider what the second half costs you. To collect the remaining fifty percent, you must hold the position through most of the remaining time — often more than half the days you have already held it. And those are the riskiest days: the closer an option gets to expiration, the more violently its price reacts to every move in the underlying. You are risking the whole position, for weeks, to collect pennies that took minutes to earn on the way in.

Win rate versus average win, in plain words

Every income strategy is a tradeoff between how often you win and how much you win each time. Holding options to expiration maximizes the average win — you keep the whole premium — but it lowers the win rate, because more time in the market means more chances for something to go wrong.

Closing at fifty percent flips the tradeoff: you accept a smaller average win in exchange for a much higher win rate, and — critically — in exchange for your capital back sooner. A closed position is capital you can redeploy into the next idea. An open position nursing its last fifty cents is capital held hostage.

Run the rough math. Ten trades, each collecting $4.00 of premium. Close each at fifty percent: you keep $2.00 per trade, $20 total, and your money is free in half the time to do it again. Hold each to expiration: some expire worthless for the full $4.00, but one or two blow up and cost you $8.00 each. The average win looks better on paper; the account usually disagrees.

What our own tape told us

This is not theory for us. We went back through our 2026 futures trading history and modeled a simple question: what if, on every trade, we had followed the mechanical rule — close at fifty percent of premium, and exit everything by twenty-one days to expiration — instead of the discretionary exits we actually took?

The modeled answer: the mechanical rule would have beaten our actual exits by roughly forty to forty-seven thousand dollars over the year.

We want to be precise about what that number is and is not. It is a modeled estimate from our own trading history — one year, one regime, our trades. It is not a promise, not a guarantee, and not a claim that the same gap exists for anyone else. Markets change, and one year's tape is one year's tape. But the direction of the finding matched the theory so cleanly that it changed how we operate: our early, discretionary exits — the ones that felt smart in the moment — were, on average, the expensive ones.

The twenty-one-day rule: never nurse premium into expiry week

The fifty-percent rule has a partner: whatever is still open at twenty-one days to expiration gets closed, period — profitable or not. If a position has not hit fifty percent by then, it has told you something. The market is not cooperating, the thesis is stale, or the position is simply taking too long. Close it and move on.

Expiry week is where premium sellers go to regret things. In the final days, an option's price becomes hyper-sensitive to the underlying — small moves in the stock or future translate into large swings in the option's value. This is gamma risk, in plain words: the closer to expiration, the faster a winning trade can become a losing one. There is no premium left worth that ride. The last few dollars of decay are the most expensive dollars in options trading, because of what they can cost you.

So the full rule, the way we run it: take profit at fifty percent of premium collected, and exit everything by twenty-one days to expiration regardless. Two lines. No judgment calls.

Why a rule beats your gut

The deepest reason the fifty-percent rule works has nothing to do with math. It has to do with you.

In the moment, every open winner feels like it should run further, and every open loser feels like it will come back. Discretion in the moment is just emotion with a vocabulary. A rule decided in advance — written down, backtested, followed when it is boring — removes the negotiation. You do not have to be disciplined trade by trade. You have to be disciplined once, when you write the rule, and then let the rule be disciplined for you.

That is the real lesson of our forty-to-forty-seven-thousand-dollar finding. The money was not lost to bad markets or bad luck. It was lost to us — to exits made by feel instead of by plan. The market will give you every opportunity to be clever. Take the fifty percent instead.