This excerpt taken from the SIRI DEF 14A filed Nov 4, 2008.
Who is entitled to vote and how many votes do they have?
Holders of our common stock and our Series A Convertible Preferred Stock as of the close of business on October 20, 2008 (the Record Date) are entitled to vote at the annual meeting. Each share of our common stock is entitled to one vote. Each share of our Series A Convertible Preferred Stock is entitled to one-fifth of a vote. As of the Record Date, 3,240,011,797 shares of our common stock were outstanding, and 24,808,959 shares of Series A Convertible Preferred Stock were outstanding.