Bet target size exceeded resulting in a loss

[Prathap]

I placed a back order for draw specifying my price and target bet profit with bet target type backers_profit:

betTargetSize: 36.57
betTargetType: "BACKERS_PROFIT"
persistenceType: "LAPSE"
price: 4.6

My expectation: The average size matched must be 7.95 or lesser (betTargetSize/price)

Actual result: Average size matched = 9.38 at price 4.9.

I'd have expected the average size matched to be 7.46 (36.57/4.9) so that the target profit of 36.57 is met. I don't understand why the size matched was 9.38, which is much higher than expectation.

Is this an anamoly or have I misunderstood how backers profit orders work?

[geoffw123]

This BACKERS_PROFIT field must be fairly new as I have never seen it before. I had quick glance at the latest API spec, it is poorly explained in there, so I am guessing here myself.

For BACKERS_PROFIT maybe you should deduct - 1 on the price to discount stake. So then

My expectation:
The average size matched must be X or lesser betTargetSize / (actual price matched - 1)

size X = 36.57/ (4.9 -1) = 9.38

That ties in with what you said you actually saw.

[Prathap]

Thanks geoffw123 , that does make sense. Yeah, it's not widely documented. Appreciate you reverse engineering the calculation

[GurkLand]

Thanks geoffw123 , that does make sense. Yeah, it's not widely documented. Appreciate you reverse engineering the calculation fun games to play

It's surprising to be able to apply this method.