<p>We examine the relationship between hosting mega-sporting events and the size of the underground, or shadow, economy. While the literature offers inconclusive evidence on the economic effects of hosting mega-sporting events, we hypothesize that the benefits may be concealed within the shadow sector, which absorbs the excess demand during major events. To test our hypothesis, we estimate the impact of hosting a mega-sporting event on the shadow economy of the host nation using a generalized synthetic control analysis. Results show that hosting mega-sporting events increases the shadow economy in the host country. This finding remains robust across various sensitivity analyses.</p>