AI Summary
This video explains how betting markets are priced, focusing on the concept of overround (the bookmaker's margin). It warns against blindly chasing apparent arbitrage opportunities, using a real example where traders lost money by betting into a false market without understanding its structure.
Chapters
Bookmakers create odds that imply a total probability above 100% (the overround). The excess over 100% is their profit margin. For example, the Grand National often has an overround of 160%, making long-term betting nearly impossible.
On a betting exchange, the back side (betting for) cannot be under 100% because you could back all outcomes and guarantee profit. The lay side (betting against) cannot be above 100% because you could lay all outcomes and guarantee profit. These constraints normally prevent arbitrage.
In a golf tournament market, Rory McIlroy's potential withdrawal due to a back injury caused the lay side to exceed 100%. This created a false market because if he withdrew, all bets on him would be void, distorting the book. He played, so the apparent opportunity vanished.
Users on a forum spotted a market where the lay side was above 100% and thought they could guarantee profit by laying all selections. However, they were in a 'first goalscorer' market where only starting players count. Many listed players were substitutes, so bets on them were void. They lost significant money.
Always understand the market rules and why the overround is distorted. A seemingly risk-free opportunity can be a trap if you don't know what you're doing.
Betting markets are carefully structured, and apparent arbitrage opportunities often hide underlying risks like false markets. Always verify market rules and the reasons behind price distortions before acting.
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Mentioned in this Video
Study Flashcards (5)
What is the overround in betting?
easy
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What is the overround in betting?
The overround is the total implied probability of all outcomes in a market, which is above 100% for bookmakers (their profit margin) and below 100% for exchanges on the lay side.
02:37
Why can't the back side of a betting exchange be under 100%?
medium
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Why can't the back side of a betting exchange be under 100%?
If the back side were under 100%, you could back all outcomes and guarantee a profit because your total stake would be less than the payout.
04:59
Why can't the lay side of a betting exchange be above 100%?
medium
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Why can't the lay side of a betting exchange be above 100%?
If the lay side were above 100%, you could lay all outcomes and guarantee a profit because your total liability would be less than the total payout you receive.
05:26
What caused the false market in the Players Championship example?
hard
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What caused the false market in the Players Championship example?
Rory McIlroy's potential withdrawal due to a back injury distorted the lay side over 100%, because if he withdrew, bets on him would be void.
06:57
Why did the MoneySavingExpert users lose money?
hard
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Why did the MoneySavingExpert users lose money?
They bet into a first goalscorer market where only starting players count. Many listed players were substitutes, so bets on them were void, creating a false market.
09:37
π‘ Key Takeaways
Bookmaker Profit Mechanism
Explains the fundamental concept of overround, which is key to understanding betting markets.
01:22False Market Due to Injury Doubt
Real-world example of how a player's potential withdrawal creates a distorted market.
06:10Forum Disaster
Cautionary tale of how ignorance of market rules led to significant losses.
08:42Importance of Understanding Markets
Core takeaway: always investigate why a market appears mispriced before acting.
11:19Full Transcript
[00:00] football betting loophole where you can make a lot of money very, very Would you a pile all of your money that you ever possibly own into this one
[00:14] strategy and make enormous amounts of money and retire to a desert island? Or would you be be a bit skeptical and have a closer look and try and understand exactly what was going on with this particular strategy?
[00:29] within betting markets, just not very often, and you have to be very careful how you approach them because a load of people chose option A in this particular strategy and it ended up costing them a small fortune.
[00:51] So before we talk specifically about what happened on this occasion, I Help you understand one really specific part of a betting market But it can also unearth opportunities for you, but necessarily if you
[01:07] the people did in this video. Um, so let us understand exactly how a betting market is priced and why that's important to this particular strategy and this particular story.
[01:22] So a phrase that you may be familiar with is only the bookmaker wins. And very often people sort of say, well, how is it that the bookmaker And the secret really is to do with the way that odds are created.
[01:37] that something will win. And what bookmakers do is they actually sell you that probability for less I haven't explained that fantastically well there.
[01:49] But if we look at a market, this should make a little bit more sense to you. exactly how the odds are created. 'cause there's an important concept that we need to learn here when we
[02:04] What you'll actually see as a set of odds in this particular occasion, it's odds of a horse winning a horse race and those odds, um, actually Now, I'm not gonna explain how to calculate that, um,
[02:21] On the BET Angel website, we actually have an odds converter. and not only will it convert it into a percentage, um, it will add them And the over round is the number that we see at the top on a betting exchange.
[02:37] all of those odds, there's only one horse is going to win the race. The over round should equal 100%.
[02:49] slippage, the margin that you're giving people on the other side of your bet. So on the backside, when the percentage is above a hundred percent, that
[03:01] sort of leaking to the other side. And on a betting exchange, of course you can bet against people and the lay side Giving away a little bit of margin on the other side.
[03:15] market represents, uh, the chance of something actually winning that event. somebody needs to make some money.
[03:28] So whether that's on a betting exchange or with a traditional bookmaker, you'll never quite get to a hundred percent and you'll never see it flip over on the other side.
[03:40] Or will you, we'll come onto this in a second, but yeah, that's So when you go to the website of a normal bookmaker, um, or you go perhaps on course to place a bed, one thing you will never find there is.
[03:55] because that's how they make money. something happening within that market. sell it to you at 105, 120, 150%.
[04:12] In other words, the difference between a hundred percent and that number is 'cause they don't want you to know how much they're making in theory. So they will generally put a much, much larger over round on, uh, than you would
[04:28] But ultimately, that's the way that bookmakers make their money. you something that has a hundred percent chance of winning for much, If you look at something like the Grand National, you'll very often see
[04:44] To 160%, which is why it's almost impossible to place a winning bet over the long term on a big race like the Grand National. There's just too much margin in it for the bookmakers.
[04:59] on the backside can't be under 100%. Because if you could buy the entire book effectively for under 100%, your maximum
[05:12] payout, um, is gonna be below 100%. So you will make money. 98% and 100% would be your.
[05:26] So on a betting exchange on the lay side, you can't go, the book can't go above 100% because if it did, you'd be able to do the opposite. You'd be able to lay an entire book for a hundred percent liability, and the
[05:40] difference between the lay over round and 100% would be your net profit. That can't possibly happen. number of distinct reasons.
[05:55] So let's explore why that can actually happen. So what you can see behind me here is the market for the players championship Would love to play on that course and see if I can land on the 17th green.
[06:10] The interesting thing about this market is if we look at the backside that's acting the way that we would behave, it's above 100% and therefore, if you backed You would lose money, but have a look at what we can see on the lay side here.
[06:25] You can see that the lay side is actually over 100% itself, If you actually have a a, a layover round that's above a hundred percent, you can effectively make money by laying everything in the field and you'll
[06:40] So what is actually going on here? Why do we find that the lay side is over 100%? could lay everybody in this field and you would be making good money.
[06:57] But the reason that the market is distorted like this is because of Rory McElroy In a previous tournament he pulled out in the third round, uh, with a back spasm, and there was a bit of doubt as to whether he would
[07:09] And if you look at McElroy's price, you can actually see that that If you dunno how I've worked that out, use that odds calculator Um, so what the market is doing is it's pricing in the
[07:25] Because if you manage to lay every selection within this market and uh, Roy Macy with withdrew, then that percent at the top of the You'd have to take 5% off of that.
[07:39] If Rory McElroy actually withdrew from the tournament, basically all those bets would be void and the entire market would look completely different. And this is often what happens within a variety of different markets.
[07:52] Sometimes you'll get reserve runners in horse races and that will distort the book, um, and create a market that is essentially a false market. But also in a number of different things, especially in sort of special bits, uh,
[08:05] selections can come in outta the market and that creates a distorted book. So it's always important to understand exactly what you're looking at. Now the funny thing about this is Rory McElroy actually did play.
[08:17] He skipped the practice rounds, had lots of treatment on his back, and he this was actually an opportunity. You could have made a lot of money if you knew that he was going to play,
[08:30] ended up sitting on a huge loss. So it's really important to understand the way a market is built because
[08:42] And if you don't understand that, then you could get into a lot of trouble. went on to Money Saving Expert.
[08:54] Uh, maybe they should have changed the title of that site But they went into the forum there and they started posting up An entire book above, um, a hundred percent and net a profit, because
[09:10] their maximum liability was only 100%. I, I think we can call you a a fool. Now, they couldn't see what the particular flaw was.
[09:23] no, actually, I've already upped a significant amount of money on this. This all comes down to what sort of market were they operating in and the market
[09:37] Scorer market, and the way that these markets are listed on a betting exchange and with bookmakers is that they put a whole list of names there in terms going to play in the match or not.
[09:52] They put these markets up, they list a whole squad of players. those other players outta the market. he did actually go on to play.
[10:07] the pitch at any one point in time. So what you were looking at, there was a classic false market. simply because there were more players in there than could possibly play.
[10:24] Necessarily that over round would look a lot more normal. But of course, on the money saving expert forum, lots of people And more and more people got involved in it and did the same thing until
[10:40] Somebody queried exactly what was happening, and all of a sudden they began to realize that not only had they not made an incredible amount of money very easily and with absolutely no effort whatsoever, they'd actually lost.
[10:54] Enormous amounts of money because whenever you go into a market, especially in a And when you look at the set of rule rules for the first gold score market, it explains what I've just said, that players will be taken outta that
[11:07] particular market and therefore they were betting into a false market. of money very, very easily and quickly with little or no effort.
[11:19] And that my friends, is why it's really important to understand exactly what you're doing in any market at any one point in time, what those risks are and why the market is behaving the way that it should.
[11:34] And typically you do get markets that are above or below the over round, And like we saw with the players championship, it doesn't mean that that reason is necessarily going to play out, excuse the pun.
[11:46] you may not be looking at properly. like a golden opportunity as to whether there really is one or not. the new people are coming into the market.
[12:02] But that's how a seemingly fantastic opportunity where Turned into an absolute disaster.