I’ve been betting on Sports and studying bookmaker markets for a few decades now. In the old days you could often find a significant difference in prices between bookies and betting exchanges such that you could place Arbitrage bets and make a guaranteed profit regardless of the sporting outcome. Those days are gone and when I spent some time working in the industry myself I learnt that most modern Corporate Bookmakers are lazy and they just copy the odds off others. That’s why the markets now look mostly the same these days...
However there is a relatively new innovation in the Sports Betting space called the Same Game Multibet (SGM) that has become fairly popular with Punters and any bookmaker that wants to compete needs to offer this new betting product. A Traditional Multibet is made across disparate / separate events and the odds are just multiplied. For example a multibet of Team A to beat Team B paying 2.00 into Team C to beat Team D paying 3.00 will give a multibet price of 2 x 3 = 6.00. The SGM is different because some of the outcomes can be Correlated and you can't just multiply them.
This is where the complexity comes in. What bookmakers need now is a more sophisticated Probability Model that can accurately determine and compensate the correlations between bets rather than just copy the odds blindly from someone else. Here is the secret. Most of them can’t do it properly and that means there is value to be found.
Some SGM options are 100% correlated. For instance if Team A to beat Team B is 2.00 and Team A to win by 13+ over Team B is 5.00 then you can’t just multiply those odds. The SGM price is 5.00 because if Team A wins by 13+ then they ALSO win the first leg of the multi. The bookies handle this ok by just cancelling or preventing the multiplication of that 100% correlated leg. However it’s where the options are somewhat, or slightly correlated that their models fall down because it gets too complicated to calculate the true probabilities.
Take a match where there is an option for Player X to score and also for that players Team A to win by 13+. These options are slightly correlated because chances are that if Player X scores then his Team will win by a good margin. Don’t take my word for it though, give it a test. Run up a few bookmaker sites and put some SGM tickets together with the same options and take note of the big discrepancies in the prices they come up with. Those discrepancies represent value that can be exploited. Good luck.
