In the stock market, a proxy refers to a legally-authorized agent who can vote on a shareholder's behalf. Typically, proxy votes are accomplished by sending in a formal document specifying how the shareholder wants to vote and authorizing agents to execute those votes.
The proxy document is technically a legal power of attorney which authorizes a third party to cast votes on the shareholder's behalf. The proxy ballot is completed by the shareholder and must be mailed in prior to the deadline set by the company.
The shareholder can specify how many of his shares should be voted and how those votes should be cast. Alternatively, the shareholder can give discretion to the proxy agent and allow them to cast the votes as they see fit.
Proxy ballots are heavily-regulated documents, and proxy statements must be filed with the Securities and Exchange Commission. Typically, these are filed on an annual basis prior to the company's annual shareholders meeting.
Proxy ballots typically contain information that shareholders might need to make an informed decision. Votes can be solicited on the replacement of directors, the appointment of external auditors or accounting firms, changes to executive compensation, and other corporate governance matters. The proxy will also show information such as the largest shareholders and the qualifications of senior executives.
Proxy ballots provide a great convenience to shareholders, allowing them to express their views and cast their votes even if they are unable to physically attend the shareholders meeting.