We examine the influence of firm ownership composition on both the abnormal returns at the announcement of a stock split and liquidity changes following a stock split. We find three results. First, the largest post‐split increase in institutional ownership occurs for firms that had low institutional ownership before the split. Second, changes in liquidity are negatively related to the level of institutional ownership before the split. Last, the abnormal return following a split is negatively related to the level of institutional ownership before the split. These findings are important as they shed new light on the source of stock split announcement returns.