Most of the substance happens before the meeting. Votes are cast by proxy card in the weeks after the proxy-statement is mailed, so the meeting itself usually just confirms a known result. Contested elections and proxy-fight outcomes are the exception.
For traders the meeting is occasionally a scheduled catalyst: approval of a merger, of a reverse-split, or of an increase in authorized-shares is a dated event with a binary outcome.
Example: a special meeting is set to approve a merger. It requires a majority of all outstanding shares, not just votes cast, so 48% turnout with unanimous support still fails and the deal is delayed.
Related: proxy-statement, voting-rights, record-date, proxy-fight