This research explores whether neural activity in response to movie trailers is consistently related to commercial success for the movies they promote. A systematic analysis of electroencephalography (EEG) recordings from a large sample of participants (n = 188) viewing a large set of movie trailers (k = 161) originating from multiple and internationally diverse datasets was performed. Several metrics that have previously been associated with commercial success—alpha, theta, beta, and gamma oscillations; alpha asymmetry; and intersubject correlations—were investigated. Only gamma activity was predictive of commercial success (box office revenue) above and beyond characteristics of the movie and self-reported liking. Importantly, the predictive power of gamma activity generalizes to new movies: Out-of-sample predictions improve significantly with gamma activity as a predictor. In addition, the findings provide initial evidence that mental processes associated with understanding and comprehension may underlie this gamma response. For movie marketing, the findings suggest that gamma activity elicited by movie trailers can be used to optimize trailers for maximum understanding and to inform prerelease marketing decisions. This work represents a significant step forward for the field of consumer neuroscience by confirming the value of EEG-derived metrics in predicting marketing-relevant outcome measures.