Stephen Shankland/CNET

Former Google CEO Eric Schmidt is planning on selling off about 42 percent of his stock in the search giant, according to documents filed with the Securities and Exchange Commission.

Today, Marketwatch reported on the expected sale, suggesting that Schmidt -- currently Google's chairman -- will try to net as much as $2.51 billion from the sale of the stock. To date, he owns as much as 2.3 percent of Google's stock, and has 8.2 percent of the company's voting power.

Schmidt currently owns 7.6 million shares of Google's Class A stock, and hopes to sell off about 3.2 million shares. The plan for Schmidt's divestiture of stock went into effect in November, but the first trade is likely to take place within about 30 days, and could continue throughout the year. Google stock is currently trading near its all-time high.

Below is the text from the form 8-K filing by Google today:

On November 15, 2012, Eric E. Schmidt, Google's Executive Chairman of the Board of Directors, adopted a stock trading plan in accordance with the guidelines specified in Rule 10b5-1 under the Securities Exchange Act of 1934, as amended, and Google's Policy Against Insider Trading. In February 2013, sales of Eric's Google stock may commence under this trading plan.

The pre-arranged trading plan was adopted in order to allow Eric to sell a portion of his Google stock as part of his long-term strategy for individual asset diversification and liquidity. The stock transactions pursuant to this trading plan will be disclosed publicly through Form 4 and Form 144 filings with the U.S. Securities and Exchange Commission. Using this trading plan, Eric can diversify his investment portfolio and can spread stock trades out over a period of one year to reduce market impact.

As of December 31, 2012, Eric beneficially owned approximately 7.6 million shares of Class A and Class B common stock, which represented approximately 2.3% of Google's outstanding capital stock and approximately 8.2% of the voting power of Google's outstanding capital stock. Under the terms of this trading plan, Eric intends to sell up to approximately 3.2 million shares of Class A common stock. If, during the one-year period for which this trading plan is effective, Google declares and pays a dividend of one share of Class C capital stock for each share of Class A common stock and Class B common stock then outstanding, then a number of shares of Class C capital stock equivalent to the number of shares of Class A common stock subsequently sold, will also be sold under the trading plan. On a pro forma basis as of December 31, 2012, assuming all shares of Class A common stock (and excluding the shares of Class C capital stock to be issued pursuant to the dividend) had been sold under the trading plan, Eric would have owned approximately 4.4 million shares, which would have represented as of such date approximately 1.3% of Google's outstanding capital stock and approximately 5.0% of the voting power of Google's outstanding capital stock.

A Google spokesperson told CNET that, "This is a routine diversification of assets and Eric remains completely committed to Google."