Arbusers

Abstract

The online sports gambling industry employs teams of data analysts to build forecast models that
turn the odds at sports games in their favour. While several betting strategies have been
proposed to beat bookmakers, from expert prediction models and arbitrage strategies to odds
bias exploitation, their returns have been inconsistent and it remains to be shown that a betting
strategy can outperform the online sports betting market. We designed a strategy to beat football
bookmakers with their own numbers. Instead of building a forecasting model to compete with
bookmakers predictions, we exploited the probability information implicit in the odds publicly
available in the marketplace to find bets with mispriced odds. Our strategy proved profitable in a
10-year historical simulation using closing odds, a 6-month historical simulation using minute to
minute odds, and a 5-month period during which we staked real money with the bookmakers 1 .
Our results demonstrate that the football betting market is inefficient ‒ bookmakers can be
consistently beaten across thousands of games in both simulated environments and real-life
betting. We provide a detailed description of our betting experience to illustrate how the sports
gambling industry compensates these market inefficiencies with discriminatory practices against
successful​ ​ clients.