Jeff Bezos just sold $1.8 billion worth of Amazon shares — here's our best guess at why (AMZN)

Amazon CEO Jeff Bezos just sold $1.8 billion worth of the company's shares in what may have been his largest stock sale in the internet company's history.

Bezos cashed in more than 960,000 shares valued at about $1,900 per share in the last three days of July, as company filings with the Security and Exchange Commission show. That represented 1.6% of Bezos' total stake in the company, and it could be the largest sale of Amazon stock that Bezos has ever made since he started the company more than 20 years ago, according to Forbes.

Bezos also transferred 19.7 million shares to ex-wife MacKenzie Bezos, making her the company's second-largest individual shareholder as Bloomberg notes. Her 4% holding in the company is worth $37 billion.

It's unclear why Bezos decided to sell off his shares at this time. To be sure, the sales were part of a so-called 10b5-1 trading plan, in which shares are automatically sold at pre-determined dates to avoid any perception of trading on insider knowledge.

Still, an executive cashing out big chunks of stock is often considered a negative sign, since it suggests the person may not be as bullish about the stock's potential as in the past.

As the owner of several other companies, including a space exploration company and the Washington Post newspaper, Bezos has a lot going on. There are plenty of personal reasons why Bezos might have sold his shares that have nothing to do with Amazon.

Here are our best guesses at where the money from his stock sales might be going, as well as some of the big issues clouding Amazon's future that coincide with the moves.

Amazon did not immediately respond to Business Insider's request for more details about the sale.