What will my option be worth on Monday?
Weekend option pricing, with the actual math
Published July 14, 2026 · Updated July 17, 2026
If the stock doesn't move, your option will be worth slightly less on Monday than it was on Friday. For a typical 30-day option, figure around 5% less. If the stock gaps, the move will swamp the decay: a 3% gap swings that same option roughly ±35%.
Those numbers come from repricing a real example with the Black-Scholes model, not from rules of thumb. The worked example below shows every figure. And you can get the exact number for your position in about thirty seconds:
Open the free calculator → Enter your strike, expiry, and implied volatility, and read Monday straight off the projection table. No signup, no account.Why "subtract two days of theta" gets it wrong
The tempting shortcut: your broker shows theta, the dollars your option loses each day just from time passing, so multiply it by the days in the weekend and subtract. Sometimes that lands close. It breaks in three specific ways.
- Theta accelerates. Theta isn't a flat daily fee; it's the current slope of a curve that gets steeper as expiry approaches. A $105 call on a $100 stock with 30 days left loses about 5.4% of its value over a flat weekend. The same call with 5 days left loses 54%. That's more than half its value gone by Monday without the stock moving a cent. The theta your broker quotes today is exactly the number that stops being a good multi-day predictor when decay matters most.
- If the stock gaps, delta has already moved. Delta, which is how much the option gains per $1 move in the stock, is only accurate for small moves. As the stock moves, delta itself changes; the rate of that change is gamma. For option buyers this works in your favor: an up-gap helps more than Friday's delta predicted, and a down-gap hurts less. But it means any estimate built on Friday's Greeks is wrong the moment the stock opens 3% away. The fix is to reprice the option at Monday's stock price, which is what the table below does.
- Part of the weekend is already in Friday's price. Nothing trades on Saturday or Sunday, but the calendar keeps running. Market makers don't wait until Monday to charge you for that. They shade implied volatility (the market's estimate of future movement that's baked into every option price) lower into Friday's close. So some weekend decay is paid before the weekend starts. The flip side: if the weekend passes quietly and IV opens lower on Monday, you lose a bit more than theta alone predicted. The example option below loses about $0.11 per volatility point, so a routine 2-point Monday markdown takes the flat-weekend value from $3.10 to $2.89.
A worked example: one weekend, three Mondays
Say you're holding a $105 call on a stock trading at $100, with 30 days to expiry and implied volatility at 45%. You paid $2.10 for it a couple of weeks ago, and as of Friday's close the model marks it at $3.27. A nice trade so far. Its Greeks: delta 0.388, theta −$0.087 per day.
The naive Monday estimate is $3.27 minus two days of theta: $3.10. Here's what full repricing says (Monday modeled at 28 days to expiry with IV held at 45%; the FAQ covers the two-versus-three-days question):
| Monday scenario | Option value | vs Friday ($3.27) | vs your $2.10 entry |
|---|---|---|---|
| Stock flat at $100 | $3.10 | −5.4% | +47.5% |
| Gaps up 3% to $103 | $4.38 | +33.8% | +108.6% |
| Gaps down 3% to $97 | $2.09 | −36.2% | −0.6% |
Values computed with the Black-Scholes model at a 4.5% risk-free rate, implied volatility held at 45%. It's the same math the calculator runs.
Three things worth noticing:
- The flat weekend costs $0.17. That's annoying but not fatal at 30 days out. Run the same table at 5 days out and the flat scenario alone is a disaster.
- The down-gap erases the whole trade. You were up 56% on Friday. One 3% dip and you're back below your entry. Decay and delta hit from the same side. This is the scenario that surprises people, and it's completely visible in advance.
- The asymmetry is gamma working for you. Measured against the decayed baseline of $3.10, the up-gap adds $1.28 while the down-gap costs $1.01. Long options gain more on a move up than they lose on the same-size move down. That convexity is part of what theta is charging you for.
Every number above is Black-Scholes output from the same math the OptionWit calculator runs, not an estimate. The table holds IV at 45%; mark it down 2 points and flat-Monday becomes $2.89, turning "annoying" into a real dent.
Model your own position
Grab four numbers from your broker's option chain: the stock price, your strike, days to expiry, and the contract's implied volatility. Enter them in the calculator along with what you paid. You'll get a full grid with dates across the top and stock prices down the side, and Monday is just a column: read down it to see your option's value if the stock is flat, up 3%, or down 3%. Set the "IV change" control to −2 or −5 to preview a volatility markdown on top.
Try it with your position → The OptionWit calculator is free, runs entirely in your browser, and reprices your exact contract for any date and stock price.Frequently asked questions
Do options lose value over the weekend?
Yes. The calendar runs whether or not the market is open, and an option with less time left is worth less. But you rarely see three full days of theta hit at Monday's open, because market makers shade implied volatility lower into Friday's close, pre-charging part of the weekend. The decay is real; it's just front-loaded into Friday afternoon rather than appearing all at once Monday morning.
Why did my option drop on Monday even though the stock went up?
A small move up can lose the race against two-plus days of time decay and a Monday IV markdown. It's most common with out-of-the-money options close to expiry, where theta is huge relative to delta. Near expiry a flat weekend can cost half the option's value, and a modest pop in the stock simply can't cover that bill.
Is a weekend two days of decay or three?
By the calendar, Friday close to Monday close is three days. In practice, part of that is already in Friday's price via the IV shading described above, so what shows up between Friday close and Monday open usually looks like roughly two days' worth. Our example uses two. Some pricing models count trading days instead of calendar days. That means bigger theta per day but fewer days, and the same destination.
Should I sell my options before the weekend?
That's a trade-off you can quantify rather than a rule to follow. Holding costs you weekend decay, which is small far from expiry and brutal near it, while selling gives up your exposure to a Monday gap. Run your position through the calculator and compare the flat scenario against the gaps you think are plausible; the table shows exactly what each outcome is worth. We can show you the numbers, but the decision and the risk are yours. This isn't financial advice.