Information for measuring the performance of a commercial action is essential for any organization. Sponsorship actions have increased significantly in the last few decades, but academics and practitioners have not yet found a suitable indicator for measuring their performance. This is the first study to propose an objective indicator—frontal alpha asymmetry using an electroencephalogram. Our goal was to investigate the effectiveness of sports sponsorships by examining both stated preferences and neural responses. We measured the congruence of the stated preferences, attitude, purchase intention, and loyalty, as well as the effective congruence. A 76-subject experiment revealed greater left frontal activity (approach behavior) during congruent versus incongruent sponsorship (avoidance behavior). electroencephalogram results were consistent with self-reports, but we found that frontal alpha asymmetry is positively related to loyalty when sponsorship is congruent and inversely related in the incongruent case. This new indicator of sponsorship effectiveness could be useful for examining the performance of commercial action at both academic and professional levels.