I’ve started making some software that determines the probability of something happening and then using betting exchanges to place BACK bets. I do understand the concept of lay bets however what I don’t understand is how to determine/calculate what price they should be.
As an example last nights match:
Hearts V Celtic - BTT - smarkets I concluded there’s a 49% chance of this NOT happening which would give me a decimal of 2.04 to BACK
So with the lay aspect would it not be the opposite = 51% meaning 1.96? Of course you can move these around more to get better value. But I’m baffled as to how some of the lays are priced and why they're priced that way and struggling to find information.
I’ve included screenshot of odds before kickoff on markets from last nights match. 2.02 BACK and 2.16 LAY?
Any help or pointers in the right direction would be massively appreciated.