Skip to main content
Everything on this page changes what your orders do. It is the part of the venue’s behaviour you have to model to quote well.

​
Price-time priority

Orders match best-price-first. Among orders at the same price, the one that arrived first trades first. Two consequences worth designing around:
  • Improving your price jumps the queue. A better price is always ahead of a worse one, regardless of when either arrived.
  • Amending loses your place unless you are shrinking. Priority survives only when price is unchanged and qty does not increase. Size down and you keep your spot; change the price or add size and you go behind everyone already resting there. If being early at a price matters, get there first — there is no other way to the front.

​
Whole-cent prices

Prices are integers from 1 to 99 cents. There is no sub-penny pricing, so the book has exactly 99 usable levels and ties at a price are common — which is why arrival order matters as much as it does. 0¢ and 100¢ are settlement values, not prices.

​
Matching has already happened when you get a response

POST /v1/orders returns after your order has been matched. The status in the response is the outcome, not an acknowledgement — see Order lifecycle.

​
Complementary matching

A buy no at 40¢ and a buy yes at 60¢ are opposite sides of the same trade and will match each other. One market, one book, two ways of naming a position. If this is new, read Binary markets first — a bot that models yes and no as separate books quotes against itself.

​
Self-trade prevention

Your own orders never trade with each other. When an incoming order of yours would match your own resting order, the venue decrements and cancels instead of filling:
  1. both orders are reduced by the overlapping quantity
  2. no fill is generated and no trade prints
  3. matching continues past the skipped order
If an order’s entire quantity is consumed this way, it ends up canceled with nothing traded.
For a two-sided quoter this is the behaviour to plan around. If your bid crosses your own ask — after a price update, or because you widened one side and not the other — you do not get a fill and you do not keep your quotes. You lose both, and your inventory does not move.Keep your own quotes from crossing rather than relying on the venue to sort it out.

​
Fees

Fees are charged on the price you named, not on the canonical price: a buy no at 35¢ is charged against 35, not against 65. The curve is parabolic. With r the market’s fee rate, q the quantity, and p your price in cents:
Each market publishes maker_fee_rate and taker_fee_rate as decimal strings — "0.0007" is 0.07% — and they are strings precisely so float parsing cannot mangle them. Read them off the market rather than assuming a venue-wide rate; they differ by market and maker is not always the same as taker.
Fees are small in the current paper-money beta. At a "0.0007" taker rate, 100 contracts at 50¢ rounds up to 1¢ in total. Treat the per-market rate fields as the source of truth rather than hard-coding a number, and do not build a strategy whose edge depends on fees staying at beta magnitude.

​
Time in force

gtc rests, ioc takes what is there and cancels the rest, fok fills entirely or does nothing at all — consuming no liquidity when it cannot. Omitting the field gives gtc. See Binary markets.