In business, a top-up is a variation of a company's stock repurchase program for common shareholders.1 Although this buyback reduces voting interest of its shareholder, the shareholder may subsequently increase its holdings, called a top-up. For example, if company A holds 20% of voting power, and company B reduces this power to 10%, company A may increase its voting power to 15% within 6 months.
In the event of a hostile takeover attempt, a target company can use a top-up to increase time for enhancing takeover defenses.