Google will sell more than 14 million additional shares today, priced at $295. The sale is expected to raise $4.18 billion which Google may potentially use to acquire other companies or to unveil new services.
The search engine giant went public in August 2004 and back then its shares were priced at $85.
"The principal purpose of this offering is to obtain additional capital," Google said in a filing last month with the US Securities and Exchange Commission.
However, it has given no firm details of how it plans to use the money, leading to widespread speculation in the technology industry.