The article in todays RP (Net Prophet) shows how someone with a bot and £100 in their account can lose tens of thousands by playing horse markets with "doubful runners" and 0% reduction factors. This could be a serious threat to punters ring fenced funds if allowed to continue.

Why? Because someone has to pay for the loss. The way I see it, the bot player should pay, but lets say the loss is beyond his finincial means. In fact someone with several thousand in their account can lose millions overnight by using poor bot software.

So who else could pay for the loss, Betfair wont be happy writing off a million each week , espeically if sharp minds pick up and exploit the loophole. So that leaves the loss in the ring fenced fund account. For the winners will rightly be paid, even though the loser will not have deposited sufficient funds into the ring fenced fund to meet the payout.

you have £200 in your account. You lay all runners to a 101% book. You now have £200 back in you account to lat the runners again. A bot can repeat this process overnight as quickly as you wish. BUT the bot is a poor bot and it doesnt take into account reduction factors. At Newton Abbot (and not for the first time) one of the horses was a known non runner (doubtful runner) so Betfair set its reduction factor to 0%. So when the non runner was taken out, instead of making a lot of 1% profits the bot, with a mere £200 in his account lost £40,000. It was reported that the bot owner sh.it himself and Betfair wrote off the debt.

But this can be expolited by teams of users, particularly if some have no way of paying the said debt, and perhaps live say in Eastern Europe. Because the winners still get paid.

This happened earlier this year on a bank holiday. The horse involved was called Eric's Charm, it was declared at 2 meetings. The trainer's second choice was in a 3 horse race where it was odds on favourite. The percentage was about 110% because of the possible withdrawal but the amount matched on this small race was about the same as that of the derby, presumably the bots at work. Eric's Charm was withdrawn at about 11.00 am. The bots' screen would have changes from all green to all red immediately.

This happened a while back on the cricket.I think the username was Systemattik and he got caught out in a market which someone had highlighted by starting a thread about a top run scorer market where the layer was guaranteed a profit.Anyway Systemattik started laying away with his £200 bank and he even came back onto the thread to thank the person for earning him a nice few quid.
A couple of hours later he became concerned when he read the rules and noticed no deduction would be made for batsmen not taking part , his concern turned to panic when someone mentioned Hayden was a definite non starter.When Hayden was taken out his guaranteed profit was to become a guaranteed 7k loss from a starting bank of a couple of hundred.
If any other players were not to play the debt would of risen , he said no way could he pay and the general thought at the time was the person starting the thread was almost certainly the backer.As far as I know we never did find out what happened and the username Systemattik has not been heard of since.Systemattik might not be the exact username but it`s fairly close.