Page and Brin currently own about 57.7 million shares of Google's Class B common stock -- roughly 18 percent of Google's outstanding capital stock and about 59 percent of the voting power of Google's outstanding capital stock.

If the two founders both sell 5 million shares as planned, they would own about 47.7 million shares, which would represent around 15 percent of Google's outstanding capital stock and 48 percent of the voting power of Google's outstanding capital stock.

Page is currently Google's president of products and Brin is its president of technology.