How the 15-minute Bitcoin up/down market settles
A new 15-minute Bitcoin up/down market opens every quarter hour, 96 a day, each asking one thing: will Bitcoin be up at the end of these 15 minutes? What "up" means is more precise than a price at the close, and it decides how the last minute plays out.
The rule
The market settles Yes if the average of an official Bitcoin index over the 60 seconds before the close is at or above the same 60-second average before the window opened, which is the previous window's official value: the strike. Otherwise it settles No. The official index is calculated every second from several exchanges' order books by an index provider; the result is usually published within a few seconds of the close.
Why the final minute decides it
Because the result is an average, every second of the final minute is locked into it for good. With 30 seconds left, half of the average is already fixed, so to change the result Bitcoin has to move about twice as far as it would have at the start of the minute, and the gap grows every second.
An example: with 20 seconds left Bitcoin is $40 above the strike, but the first 40 seconds of the final minute averaged $30 below it. If the price holds, the average lands about $7 below the strike: No. For Yes, the last 20 seconds would have to average $60 above it. A chart of the price alone would have said Yes.
How close can a price you watch get?
The official index isn't free to show, so a public tool has to use its own price. SettleMath averages three exchanges that are part of the official index, every second, and measures how far its final-minute average lands from the official value after every window.
Over the last 7 days (664 windows), our own 60-second average landed a median of $4.08 from the official value, and within $12.19 in 95% of them; it put the result on the right side of the strike in 649 of 664. The whole record, every window since our first, is on the Accuracy page.
See it live
The Live page shows every window as it happens: the model next to the market's price, the final minute's average as it locks in, and where the settlement is expected to land. The free view runs 60 seconds behind; Pro is live, with a 24-hour pass that is not a subscription (Pricing). Information, not advice.