The Kelly criterion for spread bets

The optimal betting strategy for a gambler betting on a discrete number of outcomes was determined by Kelly (1956, A new interpretation of information rate. J. Oper. Res. Soc., 57, 975–985). Here, the corresponding problem is examined for spread betting, which may be considered to have a continuous distribution of possible outcomes. Since the formulae for individual events are complicated, the asymptotic limit in which the gamblers edge is small is examined, which results in universal formulae for the optimal fraction of the bank to wager, the probability of bankruptcy and the distribution function of the gamblers total capital

Risk-Neutral Pricing and Hedging of In-Play Football Bets

A risk-neutral valuation framework is developed for pricing and hedging in-play football bets based on modelling scores by independent Poisson processes with constant intensities. The Fundamental Theorems of Asset Pricing are applied to this set-up which enables us to derive novel arbitrage-free valuation formulæ for contracts currently traded in the market. We also describe how to calibrate the model to the market and how trades can be replicated and hedged

Information Processing Constraints and Asset Mispricing

I analyse a series of natural quasi-experiments - centred on betting exchange data on the Wimbledon Tennis Championships - to determine whether information processing constraints are partially responsible for mispricing in asset markets. I find that the arrival of information during each match leads to substantial mispricing between two equivalent assets, and that part of this mispricing can be attributed to differences in the frequency with which the two prices are updated inplay. This suggests that information processing constraints force the periodic neglect of one of the assets, thereby causing substantial, albeit temporary, mispricing in this simple asset market

Bettors' reaction to match dynamics -- Evidence from in-game betting

It is still largely unclear to what extent bettors update their prior assumptions about the strength and form of competing teams considering the dynamics during the match. This is of interest not only from the psychological perspective, but also as the pricing of live odds ideally should be driven both by the (objective) outcome probabilities and also the bettors' behaviour. Using state-space models (SSMs) to account for the dynamically evolving latent sentiment of the betting market, we analyse a unique high-frequency data set on stakes placed during the match. We find that stakes in the live-betting market are driven both by perceived pre-game strength and by in-game strength, the latter as measured by the Valuing Actions by Estimating Probabilities (VAEP) approach. Both effects vary over the course of the match

Modelling of the In-Play Football Betting Market

This thesis is about modelling the in-play football betting market. Our aim is to apply and extend financial mathematical concepts and models to value and risk-manage in-play football bets. We also apply machine learning methods to predict the outcome of the game using in-play indicators. In-play football betting provides a unique opportunity to observe the interplay between a clearly defined fundamental process, that is the game itself and a market on top of this process, the in-play betting market. This is in contrast with classical finance where the relationship between the fundamentals and the market is often indirect or unclear due to lack of direct connection, lack of information and infrequency or delay of information. What makes football betting unique is that the physical fundamentals are well observable because of the existence of rich high frequency data sets, the games have a limited time horizon of usually 90 minutes which avoids the buildup of long term expectations and finally the payoff of the traded products is directly linked to the fundamentals. In the first part of the thesis we show that a number of results in financial mathematics that have been developed for financial derivatives can be applied to value and risk manage in-play football bets. In the second part we develop models to predict the outcomes of football games using in-play data. First, we show that the concepts of risk-neutral measure, arbitrage freeness and completeness can also be applied to in-play football betting. This is achieved by assuming a model where the scores of the two teams follow standard Poisson processes with constant intensities. We note that this model is analogous to the Black-Scholes model in many ways. Second, we observe that an implied intensity smile does exist in football betting and we propose the so-called Local Intensity model. This is motivated by the local volatility model from finance which was the answer to the problem of the implied volatility smile. We show that the counterparts of the Dupire formulae [31] can also be derived in this setting. Third, we propose a Microscopic Model to describe not only the number of goals scored by the two teams, but also two additional variables: the position of the ball and the team holding the ball. We start from a general model where the model parameters are multi-variate functions of all the state variables. Then we characterise the general parameter surfaces using in-play game data and arrive to a simplified model of 13 scalar parameters only. We then show that a semi-analytic method can be used to solve the model. We use the model to predict scoring intensities for various time intervals in the future and find that the initial ball position and team holding the ball is relevant for time intervals of under 30 seconds. Fourth, we consider in-play indicators observed at the end of the first half to predict the number of goals scored during the second half, we refer to this model as the First Half Indicators Model. We use various feature selection methods to identify relevant indicators and use different machine learning models to predict goal intensities for the second half. In our setting a linear model with Elastic Net regularisation had the best performance. Fifth, we compare the predictive powers of the Microscopic Model and the First Half Indicators Model and we find that the Microscopic Model outperforms the First Half Indicators Model for delays of under 30 seconds because this is the time frame where the initial team having the ball and the initial position of the ball is relevant

When the league table lies: Does outcome bias lead to informationally inefficient markets?

We study whether outcome bias persists in markets with actors who are financially incentivized to make optimal decisions. We test whether inherently noisy match outcomes from European football are correctly incorporated into prices from a betting exchange market. We find that market prices overestimate (underestimate) the winning probability of teams that previously overperformed (underperformed) in terms of match outcomes compared to their performance based on “expected goals”. This pattern is mirrored in negative (positive) betting returns on overperforming (underperforming) teams. These results suggest that even competitive market mechanisms fail to completely erase outcome bias

Partition-dependent framing effects in lab and field prediction markets

Many psychology experiments show that individually judged probabilities of the same event can vary depending on the partition of the state space (a framing effect called "partition-dependence"). We show that these biases transfer to competitive prediction markets in which multiple informed traders are provided economic incentives to bet on their beliefs about events. We report results of a short controlled lab study, a longer field experiment (betting on the NBA playoffs and the FIFA World Cup), and naturally-occurring trading in macro-economic derivatives. The combined evidence suggests that partition-dependence can exist and persist in lab and field prediction markets