The decay curve bends two ways
Time decay is not a straight line. At-the-money options decay slowly at first and then faster and faster into expiry. Out-of-the-money options do the opposite past a point: their decay peaks around two weeks out and then collapses, because a strike that will not be reached runs out of value to lose.
Everyone learns the first half of this. The chart with the curve that swoops down into expiry, usually captioned something about the last thirty days. It is correct for one strike and misleading for most of the ones people actually sell.
The two curves, same stock, same expiry
UBER at $68.40, October 17 expiry, 32 percent implied volatility. One at-the-money call struck at $68.40, one out-of-the-money call struck at $72.50.
| Days left | ATM $68.40 price | ATM theta/day | OTM $72.50 price | OTM theta/day |
|---|---|---|---|---|
| 60 | $377 | $3.32 | $211 | $3.06 |
| 42 | $312 | $3.90 | $153 | $3.45 |
| 28 | $253 | $4.69 | $102 | $3.87 |
| 21 | $218 | $5.37 | $74 | $4.12 |
| 14 | $176 | $6.49 | $44 | $4.32 |
| 7 | $124 | $9.02 | $14 | $3.92 |
| 3 | $80 | $13.58 | $2 | $1.88 |
| 1 | $46 | $23.24 | $0 | $0.06 |
The at-the-money column does what the textbook says. $3.32 a day at 60 days, $23.24 on the last one. Seven times faster.
The out-of-the-money column climbs to $4.32 around 14 days and then falls off a cliff. By the final day it is decaying at six cents.
Why the out-of-the-money curve turns over
Because there is nothing left to decay.
At 14 days the $72.50 call still holds $44 of extrinsic value, and there is a real if unlikely path where UBER covers four dollars in two weeks. At 3 days that path has nearly closed. The contract is worth $2. It cannot lose $4 a day because it does not have $4.
The at-the-money option never has that problem. It stays uncertain right up until the closing bell, so it keeps a meaningful extrinsic value that has to vanish in a shrinking number of days.
Where the money actually decays
Split the at-the-money option's life into thirds, from 60 days to expiry:
- Days 60 to 40: loses $0.72 of $3.77, or 19 percent.
- Days 40 to 20: loses $0.92, another 24 percent.
- Days 20 to 0: loses the remaining $2.12, 56 percent.
More than half the decay lives in the last third of the life. That is the real argument behind the 30-to-45 day convention: you are selling into the stretch where the curve is about to steepen, without yet sitting in the part where gamma is dangerous.
What each curve tells you to do
If you sold close to the money, closing early is a real cost. Your decay is accelerating and the last two weeks hold most of it. Buying back at 50 percent of max profit gives up the fastest part of the curve. It is often still right, because gamma is climbing at the same time, but you are paying for the safety and should know it.
If you sold well out of the money, closing early is nearly free. This is the part almost nobody exploits. Our $72.50 call is worth $14 at seven days and decaying at four dollars a day, falling. Holding it to expiry earns the last $14 while carrying full assignment risk through an entire week.
Buy it back. Pay the $14 plus the spread, release the shares, and write the next one. The premium you gave up is a rounding error against a week of being short a contract that can still be run over.
The rule this produces
Stop asking how many days are left and start asking how much extrinsic value is left, and how fast it is coming out.
- Under 10 percent of the original credit remaining: close it. There is no decay left worth the risk, whatever the strike.
- At the money with two weeks to go: the richest decay in the contract's life is directly ahead, and so is the worst gamma. This is a genuine judgment call, not a rule.
- Anything inside three days: the decay is finished on out-of-the-money strikes and violent at the money. Neither is a good place to be holding.
One more thing the tables assume: the stock sat still for 60 days. It will not. Every number above is the shape of the decay, not a forecast of the trade.
OptionsKing scores every candidate strike on a deterministic 0 to 100 scale, blends that score with the return on the capital the trade ties up, and shows you the highest-ranked handful. There is no minimum score. How it works covers what the ranking does and does not tell you.
Questions people actually ask
Does theta decay accelerate into expiration?
At the money, yes, and steeply. The at-the-money UBER call went from $3.32 a day at 60 days to $23.24 on the final day. Out of the money it does the opposite, peaking near 14 days and collapsing to almost nothing.
Why does an out-of-the-money option stop decaying?
Because it runs out of extrinsic value. At three days the $72.50 call was worth $2, so it could not lose $4 a day. The path to the strike has closed and there is nothing left for time to take.
How much of an option value decays in the last month?
On an at-the-money contract, more than half. Splitting a 60-day option into thirds, the final 20 days accounted for 56 percent of the total decay against 19 percent for the first 20.
When should I close a short option?
When less than about 10 percent of the original credit remains, whatever the strike, because there is no meaningful decay left to collect and the assignment risk continues. Out-of-the-money positions reach that point well before expiry.
Sources
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.
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Do the math on your own trade
Every price in this article is an illustrative worked example, not a quote. Read The Greeks 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.