says it all 
Feb 14, 2023 -- 1:53PM, longbridge wrote:
The only way I can imagine winning money betting IR by 'bot is on the tracks where TPD GPS feed data is available - otherwise what information does your 'bot consume to inform its betting?
now. that was either someone wanting £108 on exactly the same horse as me, at almost exactly the same time as me, at one tick under what i was looking for. or someone (afternoon paddy) was simply sticking money in front of mine to make it harder for me to get matched. and that amount just happened to be an amount i see all the time around my bets.
Hulk, there is a 3rd and more likely option in addition to your either or analysis above, namely: Betfair's X-matching algorithm.
Take this market as an example. I has the x-matching algorithm switched on by betfair and currently looks like this on the website, (Note the amount wanting to back the democrats)
USA - Presidential Election 2024 -- Winning Party 3 Runners £131,917 Matched
101.4% 98.5% Democratic Party 2.16 2.18 2.2 2.28 2.3 2.32 £51,493 £100 £1,075 £575 £49 £46 £57 Republican Party 1.89 1.9 1.91 1.94 1.95 1.96 £76,104 £57 £54 £57 £7 £167 £120 Any Other 26 27 28 32 34 36 £4,320 £17 £7 £3 £2 £17 £28
If I request the prices without the synthetic x-matching prices, i.e. the raw actual market offers
you can clearly see that there's very little real offers wanting to back the democrats, and what the website is displaying is a composite of odds & prices laying the other two runners.
Betfair profit from this x-matching by increasing visual liquidity, and by skimming the difference between the lays and the inverse composite backs.
USA - Presidential Election 2024 -- Winning Party 3 Runners £131,917 Matched
101.4% 98.5% Democratic Party 2.16 2.18 2.2 2.28 2.3 2.32 £51,493 £4 £926 £569 £2 £1 £10 Republican Party 1.89 1.9 1.91 1.94 1.95 1.96 £76,104 £57 £54 £57 £7 £167 £105 Any Other 26 27 28 32 34 36 £4,320 £17 £7 £3 £2 £17 £28
whilst I have no insight into what your market looked like prior to you placing your back at 12.5, you do mention "nothing over £14 backing or laying anything" and £108 is an exact multiple of £14, so if there was 8 x £14 offers to lay on the other runners at a composite inverse odds of 12 or less, the x-matching algorithm would indeed out pip you for a £108 back
next time it happens to you, take a screen shot if you can, it will aid your quest to find out what is going on.






