The Hewlett-Packard shareholder vote on the proposed $22 billion acquisition of Compaq will take place on March 19.

The polls will close during Tuesday’s shareholder meeting in Cupertino, California. Compaq will hold its shareholders meeting in Houston the next day.

For weeks, both sides have been mailing out proxy voting cards – white for a vote for the deal, and green for a vote against. Voters can submit multiple cards, casting and reversing their votes several times. Only the most recently cast vote counts.

While the proxy cards have been circulating for weeks, large investors and institutional shareholders typically cast their votes in the last few days or hours.

Proxy votes are sent to solicitors for each side, allowing both HP and those fighting to defeat the merger to keep an eye on developing voting patterns. By the time HP’s shareholder meeting starts, both sides will know approximately how many votes their proposals received. But if neither side attracts enough votes for a decisive victory, HP could postpone announcing an outcome.