Research on sports betting often attempts to identify biased evaluation by

bookmakers, opening opportunities for profitable strategies to bettors. Previous

studies have provided evidence for the existence of such ineffiiciencies. Since most

studies cover only a few seasons, the question of whether market inefficiencies per-

sist over time remains unanswered. We analyse the big five leagues in European

association football for fourteen seasons to detect the occurrence and duration of

market inefficiencies. While our results suggest that most biases do not persist

for a long time, we still uncover profitable betting strategies throughout the full

observation period.