Flight — one path

Pick a structure, then stand inside a single market path and advance the clock through it. Each day the chain ages, time value drains, expiries pass and assignments happen. This is the page that answers what is it like to hold this.

Building the position

The pre-flight build screen: a row of expiry dates, buy/sell call and put toggles, and a strike axis with the current price marked. — Pick an expiry, choose whether you are buying or selling a call or a put, then click a strike on the axis. The mark on the axis is where the stock is now.

The premiums shown are the ones the flight will actually book: the build screen prices against the same day-zero chain the flight opens on, so nothing shifts underneath you at takeoff, and at today's price the position starts at exactly $0.

The map holds volatility still; the flight does not That grid is drawn at day-zero implied volatility. A flight moves volatility along its own path, so later days will not match the map cell for cell. The map is for choosing strikes, not for predicting the flight.

What a day advances

The clock moves and you cannot look ahead. Asking for a day the flight has not reached is refused rather than answered — a simulator that lets you peek is a backtest with extra steps.
Expiring contracts settle first, then the book is marked. Order matters: mark first and an expired short put is still valued as though it existed, which quietly corrupts the delta, the margin and the cost basis that follows.
Assignment is real. A written put that finishes in the money becomes stock at the strike, blended into your basis, and from then on you are holding shares.

The controls worth knowing

+1 day / +5 days / to end — there is deliberately no date slider; these are the control. A slider invites scrubbing back and forth, which is exactly the hindsight the simulator exists to remove.
The volatility slider (×0.5 to ×3) re-prices today's curve with every leg's implied volatility scaled, the way a vol spike would. It changes the reading, not the flight — the path itself is unchanged. On a stock-only book it is disabled, because stock has no volatility exposure to move.
Click to pin. Clicking a chart pins a day or a price, so the numbers stay put while you look at something else. Escape releases it.

How accurate is the simulated chain?

Measured rather than asserted. Given the realized price of the underlying, a simulated option lands about 6% from what the contract actually traded at over a 30-day horizon, across roughly 162,000 observations. The error grows with distance:

Days ahead	Typical error
1 day	3.5%
30 days	12.7%

Precise at the part that can be done precisely Give it a price and it prices the chain tightly — within a few percent, verified against what those contracts actually traded at. What it deliberately will not do is tell you which price to expect, because that is the part nobody does reliably. So rather than dress a guess up as a forecast, it runs many paths and prices each one properly: the range is the answer, and every point inside it is built on the same measured accuracy.

Because that study covered particular names and a 30-day window, the dashboard refuses to quote an accuracy figure outside what was actually measured, and labels an extrapolation as one. A refusal is the honest answer where a number would be invented.

One path is one sample

A flight is a single realization, so the header also shows where it sits among all the paths that were drawn — whether this one was worse than most, and how the position fares across the whole set. A flight handed over from Suggestions can be re-flown on a stress, median or best path from the same starting point, which is the fastest way to see how much of your impression came from the trade and how much from the draw.

Saving a flight

A run can be saved to a file and uploaded later. It is replayed, not restored: the file holds the world and the opening book, not the chain, so re-flying it on newer market data produces slightly different prices. The dashboard says so when it happens rather than presenting the replay as identical.