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Lori
19 Apr 14 14:22
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Date Joined: 20 Apr 04
| Topic/replies: 50,578 | Blogger: Lori's blog
Forgive me if this has been talked about previously, I've not been on the forums as much in the last year or so.

There's something I can't understand in larger markets (In this instance specifically correct scores in the snooker, but others of that size) that I can only call Secondary cross matching.

For instance today in the current market playing around with laying Ronnie 10-1 (impossible score) brings up more money on the lay side of 10-3 (2nd fave) the more I lay. This makes sense with regards cross matching. In the simplest form in a 2 horse race, laying one at evens is the same as trying to back the other at evens. This part I understand.

What I dont understand is that in this same market (which is under a five second delay), changing that same lay bet not only alters the amount trying to back the 2nd fave score (Something like a few quid at 12s appears, which again makes sense), but theres an "echo" at 36s that does the opposite of what you'd expect. It's almost like the cross matcher is reading the crossmatching and then creating another value from that. The more i lay on 10-1, the less appears at 36s for 10-3.

Anyone understand or encountered this before?
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Report Lori • April 19, 2014 2:23 PM BST
Just to clarify, the market is a five second delay but these changes are instant, hence they're definitely internal programming thingies.
Report SHAPESHIFTER • April 19, 2014 3:41 PM BST
Alogorithms are more complex than they were about a year ago.  Definitely linked to the sportsbook. 

Cross matching much more extensive than before. 

Just an observation.
Report Lay Low • April 19, 2014 4:36 PM BST
Lori
Could the "Echo" be due the  cross matching script reacting to a bot which is reacting to the cross matching of your activity?
Report Lori • April 19, 2014 5:37 PM BST
That was my first thought, but it was reacting instantly adding as well as subtracting, so with a 5 second clock that's not possible (If it's only removing, then it could have been)
Report Lori • April 19, 2014 5:38 PM BST
and ty Shapey, I'll keep an eye out. I've still been around but I've been on smaller markets a lot of the time with few outcomes.
Report Lay Low • April 20, 2014 10:11 AM BST
Lori
That is alarming, my only explanation is that the bot I referred to is not a customer’s bot but another  betfair  source code script used for the benefit of betfair’s  bookmaking division.
Report Lori • April 20, 2014 10:24 AM BST
I think their cross-matching of in play correct scores is quite complex. They have to tell it which scores are no longer possible for instance - the cross-matching becomes more noticeable as matches progress and the market sharpens around the scores that can still happen. This happens even if nobody has bothered to put up the 1000s, which is increasingly the case.

How that relates I don't know, just thought I'd add some background. I called this secondary cross matching because I have a hunch it's re-reading their own cross matching and generating a second set of available prices from their own prices - or something like that.

Your answer is also a viable possibilty and partly why I posted this, just so others can have a look
Report SHAPESHIFTER • April 20, 2014 10:38 AM BST
First, the exchange will, of course, 'benefit' the bookmaking division.

Are they ahead of the 5 second rule?  That would be an interesting question to pose though I can't see them hoovering their own clients.  The backlash from one 'insider' leaving the firm would be a huge step backwards.

I had one idea, though.  Like yourself, I was trading football with someone and noticed it on the correct score.  He had it connected to O/U, 1x2 O/U 3.5 and correct score.  When he put up a number, we were looking at the math used to spread the bets.

He's more of a mathmetician than I and couldn't get it to work but we were positive when the bet was placed, it was triggering cross-matching (the white board looked like a scene from 'A Beautiful Mind' :) )

Then we had a theory.

Suppose you put up a lay for £50.00.

So, inorder for it to "echo" instantanously to you, here are two possibilities:

a) besides your position (since this would be obvious), when you place your order, it triggers not only the cross-matching, but 'other orders' that are 'reliant' on your position thus will 'cancel' when you cancel' or 'adjust' when parts are filled.

b) the other is that, say you put up a lay at £50 at 6.0, the bookmaker bot would put up a back at 6.40 for 50 minus X, then spreading the balance on other positions and markets.  If positions were matched, then the bot would take some of yours, etc.  So if you cancel the 6.0, the 6.40 plus related bets would all disappear.

One also has to remember that the cross-matching was brought in before the bookmaking division (that said, they would have been planning that move). 

The goal was to create more revenue, more through commissions rather than bets being unmatched then through the 'pence here, pence there' it gained.
Report Lori • April 20, 2014 10:44 AM BST
I thought it might be that I was generating two positions by having more than one lay on some scores, but the amount available on the secondary looking bet was going in the wrong direction. Of course, it shouldn't do that if my theory is right either.

Agree about the "reliant" thing.
Report jt45 • April 20, 2014 5:41 PM BST
Lori,

Lots of strange things happen on here but I'm unclear as to how the activity you described differs from the standard cross matching activity operating in markets with more than two outcomes?

If you consider a 3 outcome A/B/C win market in which cross matching is switched on and the following unmatched bets were placed on A and B:

Lay A for £200 @ 4
Lay B for £500 @ 1.5 & £100 @ 2

Cross matching would result in C being available to Lay for £50 @ 4 & £50 @ 12.

Increasing the Lay of B @ 2, leaving all the other unmatched offers as they were, would result in an increase in the amount available to Lay C @ 2 and a decrease in the amount available to Lay C @ 12. For example, increasing your Lay of B to £300 @ 2 would result in C being available to Lay for £150 @ 2 and the reduced amount of £16.66 @ 12.

Decreasing the Lay of B @ 2 would result in a decrease in the amount available to Lay C @ 4 and an increase in the amount available to Lay C @ 12.

How exactly did what you observed in the CS snooker market differ from the above?
Report jt45 • April 20, 2014 6:09 PM BST
*

Increasing the Lay of B @ 2, leaving all the other unmatched offers as they were, would result in an increase in the amount available to Lay C @ 4 and a decrease in the amount available to Lay C @ 12. For example, increasing your Lay of B to £300 @ 2 would result in C being available to Lay for £150 @ 4 and the reduced amount of £16.66 @ 12.

Decreasing the Lay of B @ 2 would result in a decrease in the amount available to Lay C @ 4 and an increase in the amount available to Lay C @ 12.
Report Lori • April 20, 2014 8:51 PM BST
You're right, thankyou. I haven't checked the numbers but it makes sense when you word it logically. My bad. When it first came in I think it treated all bets seperately, but if it's taking all of B1 and then moving to B2, it makes sense.

Cheers.
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