I have recorded some final trade prices on Betfair for the selections in my Lay systems, and in every instance the price shown on Betfair Advantage is lower than my recorded price. I can't remember which particular selection it was but the final Betfair trade price was slightly inxs of $3.00 yet the price shown on the B.A. site was $2.22. In more instances than not, the difference is not all that great but as I said it has always been lower.

Maybe the real final trade price is known only after the records on the Betfair page for a particular race are no longer accessible to the public?

I sent their customer service an e-mail a few days ago about this perceived anomaly and they replied it will be referred to their technical people.