A shareholder vote that is undertaken in order to determine if certain laws and regulations regarding corporate takeovers are to be waived during a particular corporate action. An opt-out vote, if successful, will remove certain legal restrictions that would have prevented a corporate takeover from occurring, or allow the takeover to occur sooner than it otherwise would have.
Taobiz explains Opt-Out Vote
Although corporate-takeover laws vary from state to state, they are typically structured to provide limits on the ability of acquiring shareholders to exert too much influence on takeover targets. For example, regulations typically require corporate takeovers or extensions of tender offers to obtain a supermajority of shareholder votes in order to be approved.
These regulations can be waived, however, if the target company decides to opt out of the regulatory coverage. This is done through an opt-out vote, which, in most cases, must be approved by the corporation's board of directors before it is successfully implemented.