Purpose: This study aims to evaluate the presence of abnormal returns due to stock splits or reverse stock splits in the Brazilian capital market context. Design/methodology/approach: The event study technique was used on data from 518 events that occurred in a 30-year period (1987–2016), comprising 167 stock splits and 351 reverse stock splits. Findings: The results revealed the occurrence of abnormal returns around the time the shares began trading stock splits or reverse stock splits at a statistical significance level of 5%. The main conclusion is that stock split and reverse stock split operations represent opportunities for extraordinary gains and may serve as a reference for investment strategies in the Brazilian stock market. Originality/value: This study innovates by including reverse stock splits, as the existing literature focuses on stock splits, and by testing two distinct...