First in the queue, and what it costs to get there
Two orders at the same price are not equal. The earlier one fills first, and on a busy book the difference between first and last is the difference between a working strategy and a broken one.
How the queue works
Orders at the same price are filled in the order they arrived. Modify the price and you go to the back; reduce the size and most venues let you keep your place; increase it and you lose it. The details differ per venue and are worth reading, because a strategy that requotes constantly is repeatedly giving up priority it just earned.
On a quiet book none of this matters. On a busy one, being at the back of a long queue means you are only filled when the queue in front of you has been consumed, which happens precisely when the price is about to move through your level.
- Same price, first in wins. Changing the price sends you to the back.
- Reducing size usually keeps your place; increasing it does not.
- Being last in the queue means being filled at the worst moments.
Buying priority with one tick
The cheapest way to the front is not to wait but to improve the best price by one tick. You give up one tick of edge and take the front of a new, empty queue. Whether that is a bargain depends entirely on what a tick is worth in basis points on your market.
On a gold perp near $4,450 with a one-cent tick, one basis point is 46 ticks, so a tick costs about 0.02 bp, priority for almost nothing. On the silver book alongside, the same tick is 1.47 bp, and buying priority hands back most of the spread you were trying to earn. We measured the gold case: stepping one tick inside was worth about nine cost-per-million, and an independent 24-hour measurement over 282,367 frames landed on 8.5.
- Tick value in bp = tick size ÷ price × 10,000. Compute it before deciding.
- Under ~0.1 bp: priority is effectively free.
- Over ~1 bp: you are paying most of your spread for a place in line.
The trade-off nobody mentions: priority versus staleness
Holding your place in the queue means not moving your order, and not moving your order means being the stalest quote in the book when the price walks away. That is the same condition that gets you filled by someone who knows more than you.
The resolution is not to pick a side but to set the threshold deliberately. We moved ours from 1.0 basis point to 0.2 (from 46 ticks of tolerance down to 9), and it was worth about eight cost-per-million on its own. Combined with the one-tick improvement the two add up rather than cancelling, because they fix different halves of the same problem: getting filled, and being filled at a price that still makes sense.
- Keeping priority means going stale. Requoting means losing priority.
- Set the requote threshold in basis points, not in ticks: ticks are not comparable across markets.
- Measured: 1.0 bp → 0.2 bp was worth ~8 CPM; with the tick step, ~18 together.
Questions
What is queue position in an order book?
Your place among the orders resting at the same price. Venues fill them in arrival order, so an order placed earlier at that price is filled before yours, and on a busy level the queue can be long enough that you are never reached until the price moves through.
Does cancelling and replacing an order lose my queue position?
Changing the price does, always. Reducing the size usually keeps it, and increasing it usually does not. The exact rules vary by venue and are worth reading before designing a requoting strategy around them.
Is it worth improving the price by one tick to get priority?
It depends on what a tick is worth in basis points on that market. Under roughly a tenth of a basis point it is nearly free and clearly worth it. Above about one basis point you are handing back most of the spread, and the answer flips.
How do I know if queue position is hurting me?
Look at when you get filled rather than how often. If your fills cluster in the moments when the price moves through your level, you are at the back of the queue and being selected against. Fills spread evenly across quiet and busy periods suggest you are near the front.