Due to the signaling effects, stock repurchase is perceived as a positive signal that the company’s stock is undervalued in the financial markets; therefore when a company engages in the stock repurchase, investors prefer to purchase additional shares.

A company can repurchase stock to minimize the “dilution effect” associated with exercising the stock options that have been given to employees as bonuses

When a company has more equity than its target capital structure, the company can directly change its capital structure by repurchasing. For instance, a company may issue debt and use the proceeds to repurchase stocks for adjusting its capital structure

A company can not  repurchase stock to distribute excess cash without changing the amount of dividends. Because managements are reluctant to decrease the dividends unless management is confident in the future. Also, they are reluctant to decrease the dividend because of the negative signal.