SAN FRANCISCO — Google co-founders Larry Page and Sergey Brin each plan to sell 5 million shares of their company stock periodically during the next five years, according to regulatory documents filed yesterday.

At current prices, 5 million shares of Google stock would fetch $2.75 billion. After the divestitures, they would hold 48 percent of the voting power among stockholders, down from roughly 59 percent now.