Retrospective - API Release To Prevent Minimum Bet Abuse - 19th June

[BetfairDeveloperProgram]

We made an emergency release earlier today to prevent consistent attempts to take advantage of bet rounding.

Any bets that are placed to benefit from rounding will now be rejected with the error INVALID_PROFIT_RATIO

Please see further information and example below:

If customers attempt to place a bet (including a bet used a size-up edit or price change) or cancel a bet down to a remaining size, such that it returns 20% less or 25% more [1] than it ‘ought’ to, that bet will fail with an INVALID_PROFIT_RATIO error returned to API customers – (customers attempting such on the Betfair website or mobile app will receive a generic error).

For example – a 13p @ 1.06 back bet is ‘unfair’ as it ‘ought’ to win 0.78p, but actually - due to rounding - wins 1p, a 28% uplift.

So attempting to:

• Increase the size of a £2.00 bet @ 1.06 to £2.13 (which creates a new 13p bet @ 1.06)
• Cancel £1.83 of a £2.00 bet @ 1.06 (to leave a 13p remainder @ 1.06)
• Price-editing a 13p @ 1000 bet to 13p @ 1.06 (which cancels the bet @ 1000 and creates a new one @ 1.06)

Will all fail with the error above.

Apologies for the lack of notice regarding this urgent release.

Betfair Developer Program

[jonnyf]

Hello,

I think there need to be a lot more detail provided on this. For as long as I remember, Betfair has provided a mechanism to 'green up' the market by allowing small bets to be placed. This is done by using placeOrders, then cancelOrders (with a size reduction) and then a replaceOrders to update the odds. My understanding is that this is the only method to place bets less than £2 for the purpose of greening up. My programs are now returning this INVALID_PROFIT_RATIO error (which isn't even mentioned in the API documentation!) pretty much every time a green up is attempted.

Are you saying that the API will no longer accept these type of bets at all? What is this update trying to prevent? Minimum bet size abuse or bet rounding? They seem like two different things.

[MrMagoo]

What is this update trying to prevent? Minimum bet size abuse or bet rounding? They seem like two different things.

One enables the other. Minimum bet size abuse leads to bet rounding abuse.

That there is a minimum bet size should be a clear hint that Betfair don't want you to place bets below that size. After all, they can change the limits to whatever they like. The fact that there is a 'work-around' for this size limit by placing a bet and then partially cancelling it doesn't mean that Betfair ever supported it!

[jonnyf]

Yes, but it's a workaround used by most major Betfair trading software for hedging (there's already several comments about this on the Bet Angel forums). Releasing an update to the API for something used by so many people with no warning and no documentation seems crazy to me.

[jabe]

One enables the other. Minimum bet size abuse leads to bet rounding abuse.

That there is a minimum bet size should be a clear hint that Betfair don't want you to place bets below that size. After all, they can change the limits to whatever they like. The fact that there is a 'work-around' for this size limit by placing a bet and then partially cancelling it doesn't mean that Betfair ever supported it!

I believe what you are claiming is irrelevant and incorrect.

[itsonlyagame]

This update has broken a lot of certified Betfair applications. 1000's of customers affected. Can this be rolled back and these software vendors given time to code and test their updates. Go after the abusers individually rather than break it for everyone.

[jonnyf]

At the very least, can you explain what bets will be rejected with INVALID_PROFIT_RATIO, as some bets less than £2 still seem to make it through.

[Vadimaster1]

Situation: I place a bet of $ 4, but only $ 2.5 matched. Next, I want to match up to $ 4, but $ 1.5 is no longer sent – error "INVALID_PROFIT_RATIO". Seriously?

[geoffw123]

I havent studied exactly what is going on here after this modification, but I can confirm this has broken my App too, some small stake green up attempts are now failing. (Some still work, dont know what the distinction is)
Also from reading the BetAngel forum today, lots of people are complaining that green up attemps are failing and causing them to lose money. One other person commented they were using another commercial App. today that is also now failing to green up sometimes.

TLDR: Betfair you really cant make hurried changes like this that break lots of your approved Apps !! I think this one needs to be rolled back

P.S
BetAngel have been talking to Betfair Tech Support and have already released a patched BetAngel to workaround todays rushed API change.

It would be nice if Tech support here could explain exactly what triggers this INVALID_PROFIT_RATIO error to the rest of us so we could also figure out a workaround. Thanks

[jonnyf]

I've messed around with a few API calls to try to figure out what gets rejected and what doesn't. Hopefully BF can clarify, but it looks to me like lay bets must have at least 0.8p (as in £0.008) liability to get through. So if you want to place a lay bet at 1.01 (like a green up strategy would before using replaceOrders) it has to be at least £0.80 (£0.79 gets rejected). But at odds of 1.80, you can place a £0.01 bet (at odds of 1.79, the same £0.01 bet gets rejected). I don't think back bets are affected but not 100% sure.

[geoffw123]

Hi Jonny thanks for the feedback

I didnt really catch the error properly when i saw it today on my App, so somewhat guessing here. Also it was ages ago i wrote the greenup code, so not fresh in my memory. From what I recall, the trick that everyone uses for low stake greenups is as follows

For a lay bet of 50 pence at odds 3.2
a: Place lay bet of 2.00 at oddds 1.01
b: Cancel that bet but partially of £1.50
c: Replace odds of remaining 50p fragment of bet from 1.01 to 3.2

I think with the new API change caused the Cancel operation to fail (I was left with an unmatched lay of 2 quid at 1.01)
Also the error message I got back from BF contained "sizeReduction":1.5, implying it was stage b: the Cancel operation that failed.

Hopefully Betfair will detail the change tomorrow if they dont decide to roll it back.

[Cymatic]

URGENT

This change that was intended to prevent abuse of bet rounding, has unfortunately broken various well known API software programs used by large numbers of customers, because it is preventing the software from greening up by using a lay bet with a stake of less the £0.80 (or currency equivalent).

Software needs to be able to green-up (cash-out) by using the well established long-standing procedure:
1. If the greening requires a lay bet, then send it at odds of 1.01 for the permitted minimum stake.
2. Cancel part of the bet so that it has a smaller stake.
3. Move the small stake to the required price to green-up (cash out).

I understand that there must be an urgent need for the change, but this was unplanned and is causing havoc for API software users.

So I must ask you to consider reversing this change immediately and instead just block the accounts of anyone found to be abusing bet rounding. That would at least give us the chance to work together to come up with something in an orderly manner that doesn't cause havoc for innocent software users and software suppliers!

Thank you.

[jonnyf]

FYI, for anyone trying to make their software work over the weekend while we're waiting for Betfair to sort this out, there is a workaround possible for greening up anything with odds above 2 or so:

1. If a lay bet is required, send a £2 bet at odds of 1.8
2. Cancel up to £1.99 of it (this operation is accepted at odds of 1.8, just not at odds of 1.01)
3. Use replaceOrders to move the odds from 1.8 to whatever is desired

Obviously this doesn't work for any runner with current odds of <=1.8 as the initial £2 bet will just get taken straight away. Anything with current odds of < ~2 is at risk of this happening if the market moves, but for my own programs this fixes a large percentage of API calls that failed yesterday.

[escalater]

Apologies for the lack of notice regarding this urgent release.

Thats not much use for all the havoc you have caused !!!!!!!

[Gamblr]

That's pretty bad really, not only it breaks existing software but it's also creating major delays on apps being developed at the moment (like mine..). The fact that we had to do a workaround to cashout with lower stakes was already pretty bad. If Betfair made its cashout service "public" we wouldn't need to do workarounds and Betfair would have much more control/insight over the abusive strategies.

Perhaps the abusers are premium charge payers so there's no interest in blocking such accounts